3:59

Josie hesitated. She shouldn’t have. She should have just said, “No, of course not, Dad. She’s totally fine.” But she didn’t. Just a half second while the memory of the previous night’s incident raced through her brain, but that was all her dad needed.

“I knew it. Josie, look, I didn’t want to say anything before, but I think there’s something seriously wrong with your mom. Has been for some time. I read an article about how brain cancer can radically alter a person’s personality: their likes and dislikes, even their voice and mannerisms.”

Josie gripped the phone. “You think Mom has brain cancer?”

“Maybe.”

All the blood drained out of Josie’s face. “What?” Her voice faltered.

“Er . . .” Her dad caught himself. “I mean, of course not.” He paused, and Josie could hear him drinking something on the other end of the line. “But since I brought it up, has she been complaining of headaches recently? Had any dizzy spells or blackouts?”

“No.” Josie said. Brain cancer? Really?

“Okay. Well, that’s good.” He almost sounded disappointed. “Does she ever ask about me? You know, like after you came and picked up the mirror?”

“Sure,” she lied. She couldn’t bring herself to tell him that not only did his estranged wife never ask about him, but whenever Josie brought him up, her mom immediately changed the subject.

“Good. Next time she brings me up, tell her that I’m seeing someone, will you?”

Josie’s jaw dropped. “You’ve got a girlfriend?”

“Met her at the gym. She’s a yoga instructor. Tall, blond. Kimber’s the real deal.”

“Kimber?” Josie asked. “Kimber Janikowski?”

Her dad paused. “How did you know that?”

Josie pounded the palm of her hand against her forehead. “Kimber went to my high school, Dad. She was a senior when I was a freshman.” Could her week get any worse?

She heard her dad suck in a breath. “Really?”

“She was prom queen, Dad.”

He fumbled with his phone. “Hey, Jo Jo, I’ve got a meeting. Real quick, was there something you wanted to talk about?”

Real quick. Ugh. “It can wait.”

“You sure?”

“Yep.” Never more so.

“Okay, I’ll call you later. Love you, Jo Jo.”

“Love you too, Dad.”

4:30 P.M.

Josie sighed. So much for that.

Fine. She could deal with this problem by herself. She was an only child, after all. She’d just attack it scientifically, like her parents had taught her. Josie grabbed a notebook and pen from her backpack, and settled into the pillows on her bed.

    Step one: formulate a question.

Easy. What the hell is going on?

    Step two: research.

Er, not as easy. Though she did have a few pieces of information at her disposal. The train, for starters. She could assume it was coming from Fort Meade, and therefore had dropped off a shipment of deuterium for her mom. Ultradense deuterium was central to her mom’s research into creating micro black holes. It wasn’t inherently radioactive or particularly dangerous, but Josie would have to research its properties to find out if it could have accounted for the flash.

Then there was the mirror. First the incident at the train, then the explosion in her mom’s lab—the mirror was present both times. And Josie had clearly seen the reflection of the girl—Jo, if her dreams were correct—in the mirror, and in one of those dreams, Jo had seen her in the same mirror. Not that it made any sense, but at least there was a connection.

Lastly, the time. 3:59. The flash, the explosion, the dreams. They always happened at the exact same time.

    Step three: hypothesis.

Josie absolutely rejected any kind of paranormal explanation. Nope, not possible. Everything that happened had a sound, scientific explanation. So assuming she wasn’t losing her mind, she was left with a scientific possibility. The same girl, the same room, same time. Parallel universe? There she was, back at her parents’ favorite subject. The thesis they’d both spent their careers pursuing: the many-worlds theory. Even Josie’s own attempt to prove the Penrose Interpretation was rooted in the idea that a single particle can exist in two different places at the same time. Penrose theorized that with anything bigger than a dust particle, its multiple states would collapse, so that you only ever saw the particle in one fixed position. Josie loved the simplicity of the Penrose Interpretation—none of the crazy multiple-worlds theories like what her mom had been working on for years. But if Jo was real, and her world was real—two identical particles bigger than a speck of dust existing in different places at the same time—Josie’s science-fair entry was total bunk.

Oops.

    Step four: test your hypothesis with an experiment.

That was the step that made Josie’s stomach drop. She looked up at the mirror. There was only one way to find out if that mirror was a portal to a parallel universe.

She’d have to confront the mirror. At exactly 3:59.

3:55 A.M.

Josie sat the floor of her bedroom with her blue-and-white comforter pulled over her shoulders. She’d set her alarm clock for 3:30 a.m. just in case, but it was a needless precaution. There was no way in hell she was getting any sleep that night.

Josie looked at the clock. 3:57. Come on. Why was it that whenever you were waiting for something, time seemed to slow down? It was mocking her and her ridiculous theory.

Was it so ridiculous? If the many-worlds theory was correct, if an infinite number of parallel universes existed, was it such a stretch to assume that at some point in the space-time continuum, two of them would intersect? Josie wasn’t ready to explain exactly how that might happen, but she was certainly prepared to consider it a possibility.

3:58. Josie stood up and let the comforter fall to the floor. If she was right, there was actually another world on the other side of this mirror. A world that she’d been seeing in her dreams each night. A world where a girl who was her but not her lived a life that was hers but not hers.

And if it was true, the theoretical concepts of parallel universes were about to be blown wide open.

Josie could see the reflection of her alarm clock. Any moment now. She held her breath, unable to peel her eyes away from the mirror, as the time hit 3:59.

The image blurred. Josie’s reflection distorted as if she were staring at it through a pool of water. Ripples cascaded across the surface of the mirror, obscuring her reflection entirely, then dissipated. The image resharpened and Josie found that she was staring at her own face, her own eyes once more. Only the girl in the reflection had blond highlights, bright and shiny where Josie’s hair was a duller blond, and the girl in the reflection wore a denim pencil skirt and a red gingham tank top, while Josie was in her shortie pajamas.

Not a reflection.

Josie stared at the girl. The girl stared back.

This was Jo. The girl from Josie’s dreams.

Neither said a word but Josie could tell by the look on Jo’s face that she was excited too. They’d seen the same thing, come to the same conclusion, on opposite sides of the mirror. The girl held up her hand, reaching out to touch the mirror, and Josie did the same. The surface rippled like a pebble dropping into a pond, and instead of a hard surface, the glass was soft and liquid. It was denser than water, though, and as Josie pushed her hand into the substance beyond the edge of the mirror frame, it felt like she was pressing her hand into a tub of pudding.