"All we can hope for is answers. Answers that she"-Madison jabbed her thumb in Josie's direction-"might have."

"Nick, Dr. Byrne's in a loony bin?"

Nick held up his hand, signaling for Josie to wait. Madison turned her back on them and stood panting, her arms wrapped tightly around her chest. Josie was trying to process all the information she'd just heard-ultradense deuterium, micro black holes, Tony was dead, and everyone else was missing family members-and Dr. Byrne wasn't traveling for work or on vacation. She was in an asylum. One more thing Jo didn't tell her.

Nick laid a hand gently on Madison's shoulder. "Mads, calm down."

Josie's stomach clenched. The way Nick touched her, the way his hands lightly grazed the skin of Madison's bare arms, the softness in his voice. Josie recognized it right away. They'd been intimate, maybe still were. No wonder Madison hated Jo: she was in love with Nick too.

Madison sunk her head to her chest but didn't say anything as Nick continued. "I know this doesn't make any logical sense, but I saw the mirror with my own eyes. I saw it morph away at exactly three fifty-nine. Three fifty-nine," he added for emphasis. "Is that a coincidence? I felt the concrete wall with my own hands, and then . . . I felt something close in on me as the portal closed. I don't know how to explain it, but Josie's telling the truth."

"Don't defend her!" Madison erupted. "How many more people are going to disappear because of her family, huh? I'm done with this." She walked to the corner where the generator hummed away. Over the dull noise, Josie could just make out a sob.

Silence fell. Jackson still held the gun, but it hung limply in his hand, forgotten, as his eyes followed Madison to the corner of the room. The twins wandered back to a sofa and sat stiffly side by side. Nick shoved his hands deep into his pockets and stared at the floor, kicking at something in the dusty concrete with the toe of his boot. And Josie just stood rooted in place.

"Nick," she whispered. "What's going on?"

"We've all lost someone," he said in a hushed tone as if he were in a library. "Someone who was working on Project Raze. Jackson's and Madison's dads, ZZ's aunt and uncle."

"And your brother," Josie added.

Nick stiffened. "There was an explosion at the lab. Tony and your . . . ," he started, remembering who she was. "I mean Tony and Dr. Byrne were testing a way to eradicate the Nox. That's what Project Raze is, by the way. It's a joint project between the Grid and the government. Couple hundred scientists up at Fort Meade doing anything and everything they can think of to get rid of them."

"The explosion was an accident?"

Nick narrowed his eyes and scrutinized her face for the twentieth time that day. "It was ruled an accident stemming from the calibration of the X-FEL, but it was Dr. Byrne who set up the laser. My brother's body was vaporized and Jo's mom ended up shell-shocked. She's never been the same."

"And everyone else?"

"In the days after the explosion, they all disappeared." Nick shrugged. "One by one. No trace. No evidence of foul play. No . . ." His voice trailed off.

"No bodies," Josie said, completing the thought.

"Right," he said quickly. "Except Jo's mom, who's in a military hospital near Annapolis."

The loony bin. So that's why no one mentioned Jo's mom. "Oh."

"Yeah."

"But the thing is," Nick said, leaning closer to her. "The explosion? Happened at exactly three fifty-nine p.m. Six months ago. I'm not much of a scientist, but that can't be a coincidence, can it?"

Josie took a deep breath. "No," she said slowly. "No, it can't." There was no such thing as coincidence. Everything happened for a reason, and in this case it was as if a lightbulb had gone on in her brain.

"Nick," she said quietly. She didn't really want anyone else to hear. "You remember earlier when I said a massive explosion could have caused the portal between our worlds?"

Nick smiled. "Yeah?"

"I think . . ." She paused. "Six months ago, if your brother and Dr. Byrne were experimenting with ultradense deuterium and micro black holes at the same exact time my mom was doing the same exact thing . . . well, the explosion could have weakened the fabric of space-time, pinpointed at the moment of the explosion."

"Okay," Nick said slowly. He wasn't putting the pieces together.

"Then the train. You said it yourself: the fifteenth was six months to the day after the explosion. To the very minute. Two trains, in two different dimensions, carrying the same material."

Nick looked up sharply. "Boom." He made an exploding motion with his hands.

"It's a theory, at least." She shifted her feet. "Although there must have been a catalyst for the actual flash I saw. Deuterium on its own is highly stable. It would require some sort of trigger to explode like that."

"Like?"

Josie shrugged. "Not sure." An explosion caused by the X-FEL made sense, but Josie had no idea what would have caused the flash at the train tracks. "Maybe it had something to do with what your brother and Dr. Byrne were doing. Do you know the exact details of the experiment?"

"Tony was working on an injectable for the Nox that when zapped with a powerful laser would actually create a micro black hole and suck the Nox in."

"Wow," Josie breathed. "It would trap them beyond the event horizon of a micro black hole, which would then collapse under its own mass, destroying itself and the Nox. That's brilliant. Like the ultimate flu shot."

Nick smiled. "A black-hole flu shot. I like that."

"Any idea how it worked?"

Nick shrugged. "Not sure. The remnants of the injectable were destroyed in the explosion, and Tony was the only one who knew the formula."

And that died with him, Josie thought. Her eyes met Nick's and she hoped her face didn't reflect what she had just been thinking.

Nick stood up and passed a hand through his wavy hair. "Everyone who's missing had a hand in the experiment. Jackson's dad worked on the chemical aspects of the injection. Madison's dad constructed the X-FEL prototype. ZZ's aunt and uncle synthesized some of the ingredients. Years of work went into it, all leading up to one day."

"One clusterfuck of a day," Madison said, rejoining the group. "Which was all your mom's fault."

Josie threw up her hands. "She's not my mom!"

"Whatever."

Josie tried to remain calm. Tony's and Dr. Byrne's experiment was somehow related to how Josie got there. Of that she was convinced. Maybe if she could help them figure out what happened in the lab, she'd also find a way to get home.

"Okay," she said, examining the board again. "Someone either wants to re-create the injectable or wants to make sure no one else does. That's the only way your relatives' disappearances make any sense."

The room fell silent. Josie looked from face to face as everyone avoided her eyes. She knew they were all reliving their own angst and anger over the loss of their loved ones. She felt the need to apologize, even though none of this had anything to do with her. Or did it?

Josie's mouth was dry and parched. She swallowed and continued. "And it's connected to how I got here."

"Even if you're telling the truth," Madison said at last. "Even if your batshit tale is true, how does it affect us?"

Josie shrugged. "If we know how I got here, maybe we can figure out what went wrong that day in the lab. Re-create it. If your family members are being forced to try and replicate the experiment, and we beat them to it, you have a bargaining chip."

"Exactly." Nick nodded. "And I don't know about you guys, but even if we can't get our families back, I sure as hell want to finish what they started."

Jackson kicked the sofa. "How? Seriously, we've been over every piece of their research, every note, every email, everything we could get our hands on. We can't make heads or tails of it. We'd need a couple of science geniuses to figure this out."

A slow smile spread across Josie's face. "Science geniuses? I think I've got that covered."

Madison snorted. "You? Oh, please."

"You didn't see her in physics today," Zeke said.

"It was kind of epic," Zeb added.

Nick grabbed Josie's arm. She could feel his excitement. "Could you? I mean, do you think you could figure it out?"

"Don't know." Josie shrugged. "Maybe. But I'm going to need help."

Nick tilted his head. "You got someone in mind?"

There was only one person who could handle it, and from what she'd seen, this Penelope was just as much of a science geek as her old friend back home. "Penelope Wang."

"Shit," Madison said with a roll of her eyes. "Why don't we just put a welcome sign outside."

Nick ignored her. "I don't know."

Josie's smile deepened. "You said I needed to trust you. Now it's time to return the favor."

THIRTY.

9:50 P.M.

"JOSEPHINE?" MR. BYRNE CALLED OUT FROM THE living room the second Josie closed the front door behind her, blocking out the floodlights from Nick's car that had lit her path up to the house. "Is that you?"

Damn. She'd been hoping everyone would be in bed. She was completely exhausted, and her mind reeled with a million new bits of information she needed to digest and process. She wasn't sure she had enough energy to masquerade as Jo for even a few minutes.

"Josephine?" Mr. Byrne repeated, this time more urgently.

"It's me," Josie said. "Daddy," she quickly added, remembering the way Jo always mentioned her father. She meandered over to the archway that led into the living room and leaned wearily against the wall.

"Oh, thank God!" Mr. Byrne exclaimed. He placed his tablet down on the coffee table. "I was so worried. Why didn't you answer your phone?"

Josie flinched. Her phone. She'd turned it off at the warehouse and totally forgotten about it. "I'm sorry. The . . . the battery died."

Mr. Byrne sighed and patted the cushion next to him on the sofa. Josie dutifully sat down, pulling the sleeves of her sweater down past her wrists so he wouldn't catch a glimpse of her bandages, and tried to look suitably ashamed.

"I was worried," Mr. Byrne repeated. "There have been elevated Nox sightings throughout the area. We got reports tonight of particularly large swarms between Baltimore and D.C., and there's a rumor going around that someone was attacked in our neighborhood just recently. Have you heard anything about that at school?"

Josie folded her arms across her chest, hoping he hadn't caught sight of her bandages. "No," she lied. "Haven't heard a thing."

He patted her knee. "Hopefully it's just a rumor, then. But please be careful. I can't bear the thought of losing my little girl after . . ." His voice drifted off. Josie looked up and saw that Mr. Byrne was staring across the room at a photo on the mantelpiece above the fireplace. A photo of his wife.

A wave of guilt passed over her. Here she was, an impostor pretending to be the daughter of this man who had been through so much. His wife was still alive, but in what state? She had no idea who she was or where she was. Was that better or worse than having her die in the explosion?

Mr. Byrne smiled weakly as he gazed at his wife's photo. For the first time, he reminded Josie of her own dad. "Maybe we should go see her," he suggested. "Try again."

Josie stiffened. Go see her fake mom in a mental hospital? That seemed like an incredibly bad idea. She'd been lucky with Mr. Byrne: he was distracted by work and grief over his wife, and hadn't noticed the girl pretending to be his daughter was really nothing of the kind. But a mom? Moms had a way of knowing things, of looking right through you and reading your mind. Even if Dr. Byrne wasn't quite 100 percent there, would she know the girl standing before her wasn't the one she gave birth to?

Still, the woman was suffering mental effects of a massive explosion. If she started ranting about how Josie wasn't really her daughter, they might not actually take her seriously.

Josie looked up from making her mental pros and cons list, and noticed Mr. Byrne watching her intently. He raised his eyebrows as if to say, Well?

"Whatever you'd like, Daddy," she forced herself to say.

Mr. Byrne laughed drily. "Josephine, who do you think you're kidding? You don't have to go if you don't want to. I won't force you to, okay? I know how hard it is to visit her when she doesn't know who you are."

For the first time in almost forty-eight hours, Josie felt sorry for Jo. No wonder she was so desperate to get through the mirror and find a mom who knew who she was. Josie could hardly blame her for not wanting to come back. Though maybe missing her dad would precipitate a return? He seemed like a great father and clearly cared for his daughter tremendously. Between him and Nick, maybe it would be enough to lure Jo home.

Josie smiled. "I'll let you know if I change my mind."

"Deal." He picked up his tablet and rose from the sofa, planting a light kiss on the top of her head as he did so. "Now how about you get to bed, young lady? Busy day tomorrow."

He had no idea.

3:59 A.M.

Her mom sits at the kitchen table. She rests her elbows on the laminate wood surface and holds a steaming cup of tea to her lips.

She closes her eyes and inhales deeply, relishing the aroma. "I dearly love a cup of tea," she says on a breathy exhale.

"I know."

"That woman only drank coffee. Bins of the stuff in the house, and not even a box of tea when I got here." She stares lovingly at the box of tea bags on the table.

"Oh."

"I can't tell you how many mugs of that slime I've had to choke down at the lab." She takes a long sip, then abruptly lowers the cup. "Speaking of, you'd better start making a list of what your other half did and didn't do. We can't have any suspicions if we're going to stay here."

"Stay here?"

Her mom arches an eyebrow. "Don't you want to? You don't really want to go back to all that, do you? The secrets and the lies. And the Nox."

She shudders at the mention of the Nox, then shakes her head hesitantly. "No." She pauses. "I don't know. Maybe?"

"Don't worry about your boyfriend," her mom says sharply. "He'll be fine."

Jo's stomach tightens up. "He's not my boyfriend." Not yet, she thinks to herself.

"We can't go back," her mom says with a nod of her head. "The mirror has to stay where it is. Besides"-her mom reaches across and pats her hand-"now that you're here, I don't have to worry about creating a new portal. That's all I've been working on the last six months, you know. A way to bring you here."