Nick reached over and opened the passenger door, and Josie whipped around it, careful to keep her body in the safety of the light as she climbed into Nick's car.

She slumped in the worn leather seat, panting. Interior lights of the car illuminated every inch of the cabin. And for the first time, Josie was thankful for them.

"What the hell were you thinking?" Nick asked. His voice was gruff but laced with concern and panic.

"Th-thank you," Josie stuttered. Her teeth were chattering, her body wracked with shivering. "You . . . you saved my life."

"You're lucky I followed you." Nick pulled his sweatshirt over his head and draped it over her shoulders. "What you were thinking walking home at dusk? And the path through the woods? You were practically asking for the Nox to attack."

Nox. Is that what they were? It seemed like such an innocuous word for what lurked in the dark.

Nick ran a hand through his thick, dark hair. "You're lucky you made it through the woods to the street. Most people don't make it five feet once the Nox catch them."

"Someone," Josie panted. "Someone carried me out."

"Carried you out of the dark woods?" Nick shook his head. "No one's alive in there, Jo. Not once the sun goes down."

No one was alive in the woods. That was impossible. She'd felt an arm. She'd heard a voice.

"What is with you today?" Nick continued. "It's like you're a totally different person."

"You have no idea."

"Huh?"

Josie kept quiet. It was no good trying to explain anything to Nick, since she'd be gone in a few hours and then the old Jo would bring things back to normal. Nick would just write it off as "lady problems" or temporary insanity, and Josie would pretend this sojourn into Jo's world never happened.

After a moment, Nick sighed. "Fine. Don't talk to me. I'll take you back to my house and get you cleaned up."

"No," Josie said. Her teeth were still chattering. "Take me home."

"Jo, you're covered in blood."

"Take me home," she repeated. She couldn't risk not being there for the next window. She had to get home.

"Suit yourself. But if your dad gets pissed off, it's your problem."

3:55 A.M.

Despite a half dozen Advil in the last few hours, Josie's head still pounded. Her body felt like it had been poisoned-sluggish, heavy, and aching all over.

Her ripped-up forearms didn't help matters. While the Nox, as Nick had called them, had only inflicted a few wounds on the back of her neck before she made it out of the woods, her arms looked as if she'd gone three rounds with a Weedwacker. Most of the cuts were shallow, with a few exceptions, and after a painful hour in the bathroom cleansing the deeper gashes and taping them up with gauze and butterfly bandages, she figured they'd heal okay.

But what the hell were those things? She knew now what Jo had been trying to tell her when they switched places: Don't go out after dark.

Yeah, thanks for the heads-up.

At five minutes to the appointed time, Josie was ready to go. She'd changed back into her own clothes, shoving the blood-covered yellow dress and Nick's sweatshirt deep into the bottom of the hamper, and left Jo's room exactly as she'd found it. Everything would look better now: her parents' divorce, her mom's weirdness, even Nick and her social standing at school. All of it seemed bearable when weighed against the homicidal monsters that lived in the darkness just outside the bright lights of Jo's room.

She thought she'd be sad to have to go back to her own life, but as the surface of the mirror rippled, Josie smiled. She was ready to go home.

She wanted to feel her own bedsheets; smell the musty air of her dilapidated, water-damaged house. Before the image on the other side was even fully in view Josie reached her hand into the undulating surface of the mirror.

Josie felt the thick, spongy interior of the portal as she pushed her arm through. She was about to duck into the portal and go through to her own bedroom, when her fingertips grazed something solid and rough.

Huh?

She leaned into the gooey substance of the portal until her shoulders rested against a hard surface. It was solid and heavy, and it wouldn't budge. She pulled away, and slowly, the image on the other side of the mirror came into focus. A gray concrete wall.

The wall of the basement in Josie's house.

In an instant, Josie realized what had happened. Jo had conned her. She'd conveniently left out several details about her life-a life that kind of sucked, apparently-and now that she was in Josie's life, she had no intention of coming back.

Panic. Josie reached up as far as she could, trying to find an edge, something she could wedge her fingers between and maybe force the mirror off the wall. She submerged herself in the portal, and tried to push the back side of the frame away. But it wouldn't budge. Jo must have secured the mirror with something, sandwiching it tight against the concrete.

The mirror began to ripple again and Josie pulled her body out of the portal. As her own reflection rematerialized, cold reality slapped her in the face.

Josie was trapped.

TWENTY-FIVE.

6:55 A.M.

JOSIE DIDN'T REALIZE SHE'D FALLEN ASLEEP until a knock at the door woke her up.

"Are you awake?"

Josie rolled over in bed. Her eyes were closed, but it was still dark in her room.

She stretched her arms over her head. It had all been a dream-a horrible, wretched nightmare. She was at home in her bed and her mom was waking her up so she wouldn't be late for school. Another normal day.

Thank God.

"Miss Josephine, you're going to be late."

Miss Josephine? Josie's eyes flew open and she realized she was wearing a sleep mask. Jo's sleep mask.

She was still in the nightmare.

"Miss Josephine?" Teresa cracked the bedroom door. There was a pause, then she heard Teresa take a sharp breath. "Miss Josephine, your arms. Are you okay? What happened? If your father finds-" Panic rose in her voice as each thought crossed her mind.

Josie wiggled her arms beneath the covers so Teresa couldn't see the full extent of her wounds. "I'm not feeling well, so I'm not going to school."

"But what shall I tell your father?"

Josie rolled over, turning her back on Teresa. "Just tell him I'm sick." She didn't care what Teresa thought; there was no way in hell she was going to school today. She needed to figure out a way home.

"Oh." Teresa lingered at the door for a moment, then Josie heard her slowly close it. "Of course, Miss Josephine."

Josie rolled onto her back and stared around Jo's room.

Your room.

Josie shook her head, forcing the thought from her mind. She was not going to be stuck here. She'd figure out a way home. Somehow.

What if she couldn't? She hadn't told anyone back home about Jo and the mirror. So far, she'd been able to snowjob everyone in Jo's world into believing that she was their daughter, classmate, whatever. Wouldn't Jo be able to do the same thing in Josie's world? Her mom had been so weird lately, so distant and distracted by work; would she even notice there was something different about her daughter? Would anyone?

Maybe her dad. Then again, he'd been so wrapped up in the divorce, he might attribute his daughter's weirdness to that.

There was no one else. No one who'd notice. And no one who'd miss her even if they did.

Hell, maybe people would like Jo better.

Josie swung her legs over the side of the bed and stood up. She paced the room aimlessly, her mind racing. Nick had made it clear that Jo had been after him for quite some time, to no effect. But there was another Nick. Maybe Jo would want to try with him?

And if she succeeded, she'd never want to go home.

What if Josie was stuck here? Other than Jo's father, who seemed to care for her in a kind of jovial, fatherly way, what was here for her? Josie slumped down in Jo's leather desk chair. For the first time, she prayed Madison and Nick's romance was solid and long-lasting. The only way Josie was getting home was if Jo wanted to switch back.

She sat there for what felt like hours, gently swinging back and forth in Jo's swivel chair. What was she going to do?

After a while, Josie realized her eyes had rested on an object on Jo's bookshelf. She wasn't sure how long she'd been staring at it, but suddenly, recognition dawned.

She was staring at her vase. The wine-bottle vase covered in magazine squares that she'd made in fifth-grade art class.

Josie sprang to her feet and snatched the vase off the shelf. She knew instantly that it was hers. So that's what happened to it. Her vase and Jo's vase had switched.

But how?

Josie let the vase fall back onto the shelf with a clunk. It hadn't come through the mirror with her-of that she was pretty sure. She'd have noticed a flying inanimate object. And yet here it was, as real and solid as anything else around her, which meant the connection between their worlds extended beyond the physical confines of the mirror.

And if the vases could move back and forth between the worlds without the portal, maybe she could too?

A list of things that had randomly gone missing flooded Josie's brain. Her pink tweed Converse, Mr. Fugly Bear. Things she'd looked for and couldn't find over the last week, since the mirror landed in her bedroom.

Were they here? In this house?

Josie took a deep breath. There was only one way to find out.

2:15 P.M.

Josie waited impatiently all day, but at two o'clock Teresa went out to run errands. Finally. Josie needed to spend some time perving around the house, and she much preferred to do it unobserved.

She'd spent most of the day making a list of things to look for, things that had gone missing or at least seemed odd or out of place in her house since the day at the railroad crossing. The vase, her shoes, and Mr. Fugly Bear were obvious-they were objects Josie had actively missed-but as she thought back on the last week, she realized that the leapfrogging of items between the two worlds went deeper. Incidents that seemed a mere annoyance at the time suddenly had more meaning.

Like the Tinkerbell magnet on the fridge. Josie had come home from school last week and found several pizza-delivery coupons scattered on the kitchen floor. They'd been pinned to the refrigerator door by a large Tinkerbell magnet Josie had bought on a family vacation to Disney World. She'd gathered up the coupons and found another magnet to hold them in place without really thinking about what had happened to poor Tink.

Now she knew.

And those were just the things she'd noticed. Maybe there were more objects zapped into Jo's world and vice versa? And if they could be, why couldn't Josie?

She'd already done a full sweep of Jo's room and bathroom, but other than the vase, she hadn't found any of the missing objects. She decided to start downstairs in the kitchen, the most logical place to find a refrigerator magnet.

The sleek stainless steel refrigerator was devoid of decoration: no magnets or family photos or pizza-delivery coupons in sight. Similarly, the kitchen counters were empty, just squeaky-clean granite countertops polished to within an inch of their lives. Teresa took her job very seriously.

Josie checked the pantry as a matter of course. Its contents were similar to the one in her own kitchen-it even had the same black canister set, all uniform and lined up in rows three deep on a shelf-but no kitchen magnets or anything else that reminded her specifically of home.

Josie was starting to despair when the living room, laundry room, and formal dining room all turned up empty. Was she wrong? Was the vase just a fluke?

There were three bedrooms upstairs. Jo's room she'd already gone over with a fine-tooth comb, so she tackled Jo's parents' room next. Large and luxuriously decorated, it looked more like a hotel suite than a master bedroom. The enormous king-size bed sat on a raised step on the far side of the room, flanked on either side by floor-to-ceiling windows. There was not one but two walk-in closets-his and hers-which were each about as large as Josie's bedroom back home. Not to mention the bathroom complete with sauna, whirlpool bathtub, and a glass-enclosed shower that could accommodate an entire basketball team. If Josie had a bathroom like that, she might never leave.

Searching a room that size was no easy task. But surely one of the objects on Josie's list must be there. In one of the closets, in a drawer, in the ridiculously large bathroom? Yeah, no. After an hour, Josie gave up in defeat.

One more place to check. The guest room.

Situated on the same side of the house as Jo's room, the guest bedroom was oddly sparse. Bed, nightstand. That was it. Not even a dresser, just a small closet on the far wall. Oh well, at least it would be easy to search.

The nightstand was empty, as was the space under the bed. But when Josie yanked open the closet door, she gasped.

On the floor in the middle of the closet was a box filled with a variety of miscellaneous objects. Sitting right on top was Mr. Fugly Bear.

Josie crouched down and lifted Mr. Fugly out of the box. Yep, definitely him. Missing an ear and a thumb. Her favorite childhood toy, here in a closet in Jo's house.

Creak.

Josie froze. What was that? She waited, crouched in the closet, and held her breath. After what felt like forever, Josie slowly exhaled. Just the house settling. If Teresa or Mr. Byrne were home, she'd have heard them come in. She was being paranoid.

Shaking off her fears, Josie hauled the box out of the closet. In the bright lights of the unused room, she could see another familiar object: a pair of pink tweed Converse. Then another and another. A bottle of her mom's favorite perfume. A Christmas card from Josie's cousins in Ireland. A book of tapas recipes from her mom's international-cooking phase. And a magnet shaped like the pixie from Peter Pan.

All of them here. All of them gathered and put in a box and shoved in this closet out of sight. They'd been put here deliberately. Josie shook her head. It must have been Jo. The vase might have gone unnoticed since it was so similar to the one that appeared in Josie's room, but a pair of pink Converse sneakers would have been a shock for Jo to find in her closet. Had Jo realized what they were and what they meant? Had she hidden them?

And more important, how did they get here in the first place?

Josie had no idea, but the key to getting home seemed to lie in figuring out the Mystery of the Missing Converse. She laughed lightly to herself. Best Nancy Drew title ever.

Okay, think. She leaned back against the bed. Regardless, these items had switched places with a counterpart on the other side, like Jo and Josie, only the objects were zapped at random. Josie hadn't seen these items moving through the mirror when it was open, so how did they get there?

Josie caught her breath. Maybe there was another portal?

Josie leaped to her feet. That had to be it! Another portal. Another rift between the two worlds.