The afternoon had drifted into autumn darkness and there was the barest whisper of winter chill. Abbey zipped up her hoodie and stuffed her hands into her pockets. The digital numbers on her watch read 4:46. Their parents would be home by eight o'clock, after dinner with the environmental advocacy organizations that their mother was involved in. The usual lights were on in the Forrester house. The porch light was also on, which wasn't customary, as Mrs. Forrester preferred the dark when she sat outside with her pipe. The moths fluttered and scattered as Caleb walked purposefully up the front steps and rapped on the door.

They waited, but n.o.body came to the door. Caleb knocked again, louder this time, the bones of his knuckles echoing against the old pressed-wood door. The house remained silent.

"That's weird," said Caleb. "They never go out at night." He banged a third time, and then placed his hand on the doork.n.o.b. Before Abbey could say anything, he turned it slowly and pushed the door open. A patch of yellow light from the kitchen appeared and expanded on the porch. The heavy scents of garlic and cooking oil followed. Caleb leaned his head in.

"h.e.l.lo? Anybody home?"

The door swung inward with a groan. A cutting board with sliced carrots, broccoli, and peppers sat on the countertop. The paring knife lay beside the tidy piles of vegetables. A pot and a frying pan perched on the stove burners, the lidless bottle of soy sauce between them.

No answers came to Caleb's greetings, so he and Simon stepped gingerly across the threshold. Abbey slunk into the kitchen behind them, Farley's claws skittering on the linoleum. Cooked chicken remained in the frying pan and the pot contained rice that still had the vague suggestion of warmth. Two half-full gla.s.ses containing amber liquid sat on the table.

"Looks like they left in a hurry," said Simon.

Caleb smelled the contents of the gla.s.ses and made a face. "Hard alcohol. Do you think Mark drinks? Or do you think someone else was here?"

"I don't know," Abbey said, backing toward the door. "But we better get out of here."

Simon followed her to the porch while Caleb did a final tour of the kitchen. He spent a few minutes inspecting the rotary phone on the wall, and then suddenly disappeared down the hall.

"Caleb!" Abbey called. "What are you doing?"

There was no reply. Abbey prepared to launch through the doorway after Caleb, but Simon grabbed her arm and shook his head slightly. She let out a yip of impatience. A few seconds later, Caleb came back into the kitchen. He reached into the recycling bin, withdrew two jars, and poured a small amount of the liquid from the gla.s.ses into each. Then he joined them on the porch, carrying the two jars. They closed the door and scurried away to stand on their side of the road by the hedge, just outside the moon-like circle cast by the streetlight.

"What were you doing?" Abbey hissed.

"Checking for their car," said Caleb. "It's there. Wherever they went, they either walked or someone else drove, and judging from the temperature of the rice, they must have just left. Do you think we should we go look for them?"

Simon looked ghostly in the near-darkness, like a wraith, his hood casting a shadow over his face. "No, we shouldn't. They could be just fine. We could be jumping to conclusions."

"We should go home and do our homework and eat," Abbey said. She wanted to feel the safety of the walls of their house around her. "We can watch and see when they get home." If they weren't kidnapped, she added silently in her mind. Or murdered.

Caleb thrust the jars at Simon, pulled out the list, and flipped it over to write on the back. Abbey wondered if Caleb was writing 'missing Forresters' amongst the other clues.

Caleb twirled the pencil in his fingers. "Before you go inside and stick your head in a book, Ab, we need to think this through. We must've jumped further into the future the first two times. We know when we went to New L.A. it was 2036. And if we're guessing we just jumped ahead about ten years, we know in ten years Mom and Dad will still be driving the van, and it didn't look like there was s.p.a.ce travel or people living in bubbles. So, I'm guessing the Bubble City was also further in the future. So, what was different about last time? Why didn't we go as far? Is it just random?"

Simon sprawled his long limbs onto the curb and set the jars down next to him. Abbey studied her shoelaces and looked up at the stars that were beginning to appear. She wondered if she would ever fly Twinkle-Free Air. She returned her gaze to the pink st.i.tching in her green sneakers and debated whether or not to say anything. She wanted to go inside. But then she gave in. "The difference is Farley went first."

"So?" Caleb lifted an eyebrow.

"So..." Abbey ground her sneaker into the mottled pavement. "Simon went first over the stones the first time, and I did the second time. When we were in the Bubble City, there were moments when I felt as crazy as Farley was acting when we walked down to the house. I can't describe it, but when we were in Bubble City, it was like I knew too much, and everything had meaning for me. That was my favorite periodic table on the door of that office...and that tree seemed familiar...and I felt like I'd designed that maze myself."

Caleb looked blank, but Simon nodded slowly. "That's how I felt in the s.p.a.ceship. Every programmer has their own style and tics-and when I was looking at that computer code, it was like it was so identical to something I could have written that I felt like I might have actually written it."

Abbey jumped in. "And that explains how the computer had your retinal scan in the database and knew your name, and why the code pa.s.sword system matched the pa.s.sword system you use."

Caleb glared at them both. "Could someone please explain what you're talking about?"

"The future is determined by who goes through first, I think..." Abbey said. "The first time was Simon's future, the second time was my future and the last time was Farley's future. We could only jump ten years ahead in Farley's future because that's probably all he'll live." Abbey's voice got all twitchy again at the thought of the old and lonely Farley in the future. The Farley of the present licked her hand. "Except, I guess that kid was the first through when we went to Simon's future. Maybe he and Simon have the same future. I don't know."

Caleb looked from Abbey to Simon and back again.

"I know," said Abbey. "It doesn't make any sense scientifically. But I could just feel it the whole time."

Caleb c.o.c.ked his head. "Feel what?"

"I don't know. I really can't explain it. Familiarity. Like there was weird truth in it somehow. Is that how you felt, Si?"

Simon nodded. "Sort of. It felt like I knew what I was doing, like I had all the right answers and understood how that computer system was structured, the logic behind it."

Caleb stood for a few minutes with his lips pursed before pulling a freckled hand through his crown of unruly orange hair. "There's only one thing to do then. We need to go back through, and I need to go first."

Abbey jerked her head up. She had allowed herself to stray too far from the scientific method, and now she was foundering in an abyss of half-baked hunches. "Wait. No. I don't think you should act based on a feeling. I was just about to say that feelings are often wrong. We need more evidence. We should ignore everything Simon and I just said. It's crazy-talk."

"That's why we need to go back through, and I need to go first. To get evidence," Caleb said.

Abbey studied her brother. She could not let him go back across the stones. "There are all sorts of problems with our hypotheses. How did we get home from the Bubble City? Why did that set of stones appear just outside the lab building? Are there two sets of stones? Or did they move? There are just too many variables."

Caleb's face became impa.s.sive for a few seconds. Then he c.o.c.ked his head to one side, drew his eyebrows together and grinned at her. "I think you're just trying to lead us astray with your variable talk. Isn't it best to solve multi-variable equations by picking off one variable at a time? In this case, the question of whether the future we go to is determined by who goes first?"

Abbey ground her teeth together. "Maybe."

"So, let's go!" Caleb turned to head back up the hill, his eyes bright.

"Right now?"

"Yes, why not?"

"Because I'm hungry, that's why." She didn't add that she was also scared. Abbey looked pleadingly at Simon, who had his arms crossed over his chest and a noncommittal expression on his face.

Caleb wheeled back around wearing the big-eyed look that worked famously with the girls at Coventry High. "Come on, guys. It's the last night Mom and Dad will be out late. Tomorrow night we have to be at Mom's dumb campaign party. We have to do it." He widened his eyes further.

"We have to eat, too," said Abbey.

"So, we go pack a sandwich or two and take it with us. Come on, Ab...please. For me? So I can understand. To help us figure this out. We don't have to stay long. We can just go through and see how I feel and then turn right around and come back."

Simon c.o.c.ked his head. "All right. I'm in." Without waiting for Abbey's answer, the two boys headed toward their house. Simon carried the jars of liquid.

Abbey followed behind, dragging Farley, who'd spotted a neighborhood cat and decided he'd prefer to stay out and about. Her mind scrolled through all the things that could go wrong.

"I don't want to go," she announced when they reached the house. "This is getting too dangerous. The Forresters are missing, some creepy guy named Mantis seems to be after someone named Sinclair, we have no idea who Fly Kid is, or where he is, and we have no idea what we're doing."

"You don't have to go," said Caleb. "We'll go alone. We won't be long. We promise."

Abbey sank onto the kitchen nook bench silently. Salami, cheese, and mustard sandwiches were made with more speed than she'd ever seen her brothers dispatch in the kitchen. Three sandwiches, she noted. She thumbed through her chemistry textbook at the table. Her heart clunked around in her chest like the rusty piston of an old steam engine as her brothers packed the sandwiches into a backpack. Simon tossed in a bag of chips, pears, and some juice boxes, while Caleb returned with his arms full of stuff-their father's hunting knife, a compa.s.s, flashlights, a desktop atlas, a pen and paper, scissors, twine, hats, and sungla.s.ses.

"Looks like you're going for a month, not fifteen minutes," Abbey said.

"This is all just in case, Ab. This should be our standard gear when using the stones," said Caleb.

Caleb and Simon donned hoodies and shoved their feet into sneakers.

Abbey pouted. She couldn't believe they seemed so willing to leave her behind and alone in the house, but she ignored them. As the door closed and their footfalls retreated from the porch and driveway, she walked to the living room window that overlooked Coventry City. The shadows had slipped up the sides of the house in the last fifteen minutes as evening proper descended. The streetlights in the city below connected the avenues like a pearl necklace. Where were the Forresters? What had happened to them? She wanted to run up the hill after her brothers. To the stones.

She'd almost convinced herself to retreat to her room to do her chemistry lab when she heard the quiet squeal of a high-performance car engine accelerating. The car lights flooded up the road as the silvery blue jag wheeled to a stop in front of the Forrester house. Abbey dropped to her knees in the window as a tall figure in a trench coat stepped out of the vehicle and slunk up the Forrester's walk. Abbey ran, half-crouched, to the top of the stairs. She slid her fingers under Farley's collar. Her legs wobbled as she descended the stairs into the bas.e.m.e.nt, pulling the large dog with her, straining to listen for the sound of their front door opening over the hammering of her heart.

She slipped on a pair of sneakers that were beside the bas.e.m.e.nt door and, with her fingers still wrapped around Farley's collar, slipped out into the night.

The temperature had dropped substantially in the past half-hour and the cold sliced through her thin t-shirt. She ran across their back lawn and leapt up the low retaining wall into their neighbor's yard. Farley trotted obediently beside her as she wove in and out of the dusky forms of tricycles, scooters, and sand toys. Once she reached the side of their house where she could no longer be seen from the Forresters', she made a beeline for the woods, all the while expecting to feel the chill of breath on her neck or the grip of a hand on her arm. She accelerated once she was under the cover of the forest, but each shadow became a man in her mind, and the ominous stillness of the trees propelled her to even faster speeds. By the time she reached the stones, she was nearly hysterical. She ran across the stones without letting go of Farley and the familiar wrench of the traveling was almost rea.s.suring.

When she stopped moving, Abbey looked all around her. The darkness had not receded. In fact, Abbey realized that this place was even darker than the forest she'd left. She could make out nothing except for the dark forms of trees around her, denser and more overgrown than the forest she'd departed. She could hear her own breath, but not Caleb or Simon. Farley let out a low whine.

"Caleb! Simon!" Abbey cried softly in a voice that sounded very close to tears. n.o.body answered her call. She bit back the panic and called again. But there was no answer. To her left, Abbey could just barely make out a faint glow through the trees. Farley pulled in the direction of the glow, whimpering.

"Farley, do you know where they are? Farley, find Caleb and Simon. Find Caleb and Simon."

The large dog strained at his collar, bouncing from front paws to back paws, and let out a few growly barks.

"Oh, Farley, I hope you know what you're doing," said Abbey. She realized she'd tucked his leash into her pocket. She withdrew it and fastened it to his collar. Farley started to bound off into the woods, wagging and sniffing. "Farley, wait! Stop! We have to mark the stones!" She dug her heels into the forest floor and pulled the eighty-pound dog to a halt. She whirled back into the absolute darkness. She'd already come too far away. Were the stones five steps back? Eight? Slightly to the right or to the left? Her lips felt dry and fear curled around her stomach. She had no idea.

She tried not to allow the tears to roll down her cheeks. How would she get home? Should she stay here and hope Caleb and Simon came back, or go looking for them? She should stay near the stones. But Farley started to growl into the bushes behind her-a type of low, threatening growl that he'd never emitted before in his life-and she heard the unmistakable sound of twigs snapping. She started walking blindly in the direction of the light, away from the sound, letting Farley lead the way, as branches scratched her face and tore at her hair.

Farley set a lively pace, and she was pulled along at a half-jog, half-trot, trying not to whimper as she got farther and farther from the stones. Closer to the light, the sounds of voices and drums started to reach her ears, and she realized the glow was a giant bonfire. It was in a large clearing and a raucous party was in progress. Bodies of all sizes danced around the flames to a wild drumbeat and an unruly fiddle melody. Farley slowed automatically, unsure how to proceed.

Men, women, and children held hands and circled the fire, weaving in and out of each other in an intricate pattern. Faces and arms were smudged with dirt and hair was tangled and wild. Their clothes appeared to be a mishmash of modern-looking garments, ripped and stained, and loose-fitting shifts of earthy tones. Chickens meandered around the clearing. A motley collection of teepees and tents ringed the party.

She peered from behind a clump of trees. Farley seemed completely bemused. Abbey felt the sick slink of uncertainty. Were these people friendly? Or would they boil her in a pot? The thought of heading back into the black forest alone almost made her retch. Where were Caleb and Simon? Then she caught a glimpse of Caleb in the crowd. Abbey moved forward, pushing aside branches to get a better look. Caleb danced energetically with the others, his movements graceful, his face glowing with his unmistakable lopsided grin, red hair illuminated by the fire. But he'd changed his clothes, and Simon was nowhere to be seen.

Abbey edged a bit closer. She had to get to Caleb. She'd managed to get within a few meters of the clearing without being noticed when Farley gave a yip of recognition and charged off in Caleb's direction, wrenching the leash from her hand.

"Bad dog, Farley, BAD DOG!" Abbey shouted. But it was too late. The dancers stopped to stare while Farley jumped all over Caleb. Caleb threw up his arms in surprise. Burly, hairy men in animal skins armed with bows and arrows arrived at a run, pulled Farley off of Caleb, and wrestled the dog to the ground. Farley, completely unused to being so manhandled, dropped to the ground as if he'd been shot, and for a second Abbey feared he had, but then two of the men sat on the dog's rump. Farley let out a whimper, but seemed unhurt.

Several of the armed men had already run into the bushes during the commotion, and Abbey found herself quickly surrounded, as all eyes from around the campfire turned toward her. At the men's prodding-with arrows notched in bows-she stepped into the clearing, her face flaming and her heart hammering so hard she was nauseated. She was guided toward Caleb, who stood alone by the fire, a ring of people around him. What was Caleb doing? He'd made some gesture and the men on top of Farley had risen. One man remained by the dog's side, clutching the leash tightly against the dog's neck.

As she approached, Abbey realized with utter sinking sickness that the person she was walking toward was not Caleb, not a boy at all, but a man of about fifty, with broad shoulders, a haze of red gray stubble, and a gaunt sculpted face marked by a criss-cross of deep red scars. He, too, wore the skin of an animal on his back. His shirt was open at the chest, revealing a drift of ruddy chest hair and a wooden necklace carved into the shape of the sun.

She was delivered to him, and he raised his hand to the men. "It's all right. She's with me, my niece, come to give us word of the doings of our friends the Dog Tribe." He waved his hand at Farley. "She and I will retreat to my tent where we will have word and refreshment. Let the party continue." He drew her into his arms and engulfed her in a giant bear hug, the hard muscles of his arms pulling her tight. "You are welcome here, Abbey," he whispered. His manner of speaking was slower, and more formal and serious, than that of the Caleb she knew, and his eyes were etched with a gravity and strength she'd never seen in her twin. And yet he was Caleb. And she wanted to weep.

Then the man who was Caleb, but not Caleb, took her arm and guided her away from the fire. The man holding Farley followed at a respectful pace. The fiddlers started up and the lively polka resumed with the dancers once again joining hands. The crowd parted way for them to pa.s.s and, apart from a few mildly curious stares, most people returned to their revelry.

Caleb, who wasn't Caleb, led her to a larger teepee-style tent set apart from the others. Sentries stood by the doors in furred costumes. Inside, the tent floor was covered with rugs, and two wooden torches wrapped in some sort of cloth made shadows dance across the cream walls.

"Sit," he said to Abbey. She obeyed. This Caleb was to be obeyed. "Leave the dog and bring dinner please," he said to the man. Unloosed, Farley flung himself at Abbey, burrowing his way into the blankets by her side. Once the man had left, Caleb turned back to her.

"You're Caleb," she said. It was a statement more than a question.

He smiled. The impish appeal of his looks hadn't been lost in the web of scars he now wore. "Yes, I am. You've come through the stones, I a.s.sume."

"Yes."

"Where are Simon and I? That sounds funny, doesn't it? 'Where am I?'"

Abbey smiled too, but hers was more forced and watery than her twin's. "I don't know. I came through later. You were gone. The younger you, I mean." Abbey checked her tears. It wouldn't do to cry in front of this Caleb. "But why don't you know already? If you're the future Caleb, you would know what's happened."

The green eyes that matched hers studied her. "No, I don't exactly, because you never told the past me, and I would ask that you don't." His eyes became more distant. "There was a time when I thought knowing the future would be advantageous. But now, I'm not so sure. If I'd known how things would turn out, I would've second-guessed every decision I've made in the past thirty years, and if I'd done that, things could've turned out worse. And it's important, for your safety, that I don't know too much. Timelines are sensitive-and if you change the timeline from this side of the stones, you'll be at risk. Had I known you were coming tonight, I might have sent someone out to meet you, or even come myself. That might have changed the timeline. So, it's better that I didn't know. It's also best that you don't tell the younger me much, either, for the same reasons. So, not another word. It might change something. Do you know the rules yet?" Abbey was about to shake her head when he waved his hand at her urgently. "Actually, don't tell me that either, because then I'd be able to figure out when you're coming from, which might not be a big deal, but then again it might be. Please, not a word to me, or Simon, about anything you've seen here. Just say you saw a group of people dancing. The less either of us tells the other tonight, the better. The observer effect, you used to call it. I'm more superst.i.tious than I used to be, I'm afraid."

Abbey shook her head. It was all too much to process. Her voice quavered when she spoke. "But I don't know how to get back. I don't know where the stones are."

"You can always get back, unless you break one of the rules."

Abbey felt vaguely hysterical. She started to say, but how can I be sure not to break the rules if I don't know what they are? But then she remembered Caleb had told her not to tell him whether she knew the rules, and she clasped her hand to her mouth.

The old Caleb didn't seem to notice the slip. "Please. Let's enjoy each other's company for a little bit." His eyes grew sadder, if that was possible. "I haven't seen you in a long time. You should eat, and then head back the way you came. I'll send someone with you part of the way. The woods are safe. We're in peace right now and we've got this area pretty tied down. You've got Farley." He gave the dog an affectionate rub between the ears. "I wish I had a Farley now." Farley made a rumbly sound, the one they'd always called his 'moo'. She wondered if this Caleb remembered that.

The flaps of the tent parted then, and a man arrived with two steaming bowls on a tray. Abbey's stomach growled ferociously. Simon and Caleb had taken the sandwiches. The man handed her a bowl and, with a nod from Caleb, she dug in. The stew had a gamey flavor and contained spicy meat, root vegetables, and rosemary, and it tasted divine. Abbey guessed the meat was rabbit. She gobbled it up and allowed the comfort of the food to flow through her. She watched her brother eat, the tired lines on his face moving in the candlelight, this man who lived in a tent, who had obviously seen battle, who led other men, who had once been her brother. There were so many things she wanted to ask him, but she dared not.

When the bowl was empty, she looked at her brother in alarm. Was he going to make her leave? She felt safe in the tent with this older Caleb. Safer than she'd felt since Sunday. She checked her watch. 6:42. If time pa.s.sed at the same rate here as it did at home, their parents would be home soon. She had to get back, and hope that Simon and Caleb did too. She stood.

Caleb nodded as if he agreed with her a.s.sessment that it was time to leave. "When you said I can always get back, you meant that there isn't just one portal, one way back?" she asked. "Like when we were in the Bubble City. We just came home, even though we hadn't gone back to the stones. Or is there more than one set of stones in each place? I guess you can't tell me."

Caleb smiled, the deep lines around his eyes creasing and indenting. "No, I can't. Just remember-it's about what you came for, which isn't always what you think you came for. Some people believe the stones are alive." He rose. "I'll have someone walk you into the woods. I can't do it myself. The stones you came through are south of here. Use Aquila as a guide. I don't know where you are in your timeline, but I can make some guesses. I don't know what you know already, but the stones are dangerous. They can consume you, and become all you think about. Be careful. I know you were always the level-headed one and I should have listened to you more. But I doubt there's anything you could've changed anyway. You can kill yourself trying to change the future. Don't let false prophets lead you astray."

"Please," Abbey begged. "Can't you tell me more?"

Caleb shook his head.

Abbey nodded, wordless. She wanted Caleb to be going with her. This Caleb, who seemed to be her father, or an uncle, or a much older brother. Not her twin.

At Caleb's call, a fur-clad man came to the door. They exchanged a few murmured words and then the man nodded to Abbey. Abbey heard the man say, "Yes light."

"Rowan will take you as far as the beaver pond."

Abbey stuck out her hand. Caleb took it in his and pressed his other hand against it. She suppressed a sob. Questions flashed through her mind: Where am I? Why are you so sad? What happened? But she couldn't ask them. "Thanks for the food," she said.

Caleb nodded slowly. He picked up a blanket from the tent floor. "You'd better take this too. It's a cold night."

Abbey, Rowan and Farley left the tent and skirted the dancers, who now moved in unison to a quieter, more graceful dance that reminded her of Tai chi. The dancers stopped at various intervals in their routine and cupped their hands together as if they were holding something, before raising their palms to the sky with solemn expressions. Abbey realized it was a permanent camp. Makeshift wooden structures stood off in the trees. Wooden sheltered cookhouses, with low fires and bubbling pots, were scattered at regular intervals throughout the tents. Her brother would be spending winter here. The warmth she'd felt in the teepee began to subside, and she pulled the blanket tightly around her.

Rowan resembled a hairy warthog with black bristles protruding from every place imaginable on his face. He'd looked friendly enough in Caleb's tent, like a droll beast with an unfortunate follicle problem, but in the dwindling light, the excess hair made him wilder, unrulier. He marched purposefully in silence until they were away from the camp, and then he slowed his pace. Abbey felt a twitch of unease at the change in speed.

"Where are you from?" he asked.

Abbey grasped desperately for Caleb's words at the fire. "The Dog Tribe," she repeated.

"And where do your people live?" Something about his tone suggested interrogation rather than casual inquiry. The sauntering seemed too deliberate, too uncalled for, like he was killing time, circling her into a trap.

She searched again for an appropriate answer, glancing back at the fading light of the fire to determine if she could run it, but she'd seen the daggers hooked into Rowan's belt and imagined how quickly one might be placed in her back. "Circle Plateau," she said, not knowing why she'd pulled this out of the air, but hoping it was sufficiently generic to pa.s.s.

"Long walk," Rowan said. "These woods aren't safe for a girl traveling on her own."