Marcus inched open the door that led into the next classroom. He poked his head in, then audibly exhaled. “It’s empty.”

We all piled into the room—from the algebraic equation on the board, a math room—and closed the door. This was a good plan, I told myself. Use the inter-classroom doors to avoid the hallway. And when we got as far as we could, we’d make a run for it to the nearest exit.

The only thing that could ruin this plan was if a zombie was actually in one of the classrooms. Which I was sure we were all thinking about, since the others looked as nervous as a bunch of gazelles in lion territory.

Charlie looked at the numbers on the board. “Why did the bacteria fail the math test?”

“What?” Marcus asked.

“He tells science jokes when he gets nervous,” I whispered.

“Oh,” Marcus said. “Um, okay. Why did the bacteria fail the math test?”

Charlie answered, “They thought multiplication was the same as division.”

No one laughed.

“Get it?” he said. “Because bacteria cells divide and—”

“Yeah, we get it,” Willa cut in. “It’s just not the best time right now, Charlie.”

Frowning, Charlie put his ear against the door to the next classroom. “Sounds empty.”

He outstretched one trembling hand toward the knob.

Willa reached out and grabbed his other hand. Charlie’s eyes widened, and he looked down at her clasped fingers like they were some strange foreign object he’d never seen before. But he held on tightly.

I’d been starting to suspect that Willa had a crush on Charlie. And I hadn’t yet decided how I felt about it. But now wasn’t the time to explore those feelings. Plus, Willa holding his hand seemed to be useful, because Charlie was suddenly more confident. His shoulders squared, and he flung open the door.

The classroom was dark but quiet. Charlie and Willa crept inside. Marcus and I followed, running our hands along the wall looking for the light switch. I found it and flicked it on, just as something made a huge crash.

My eyes adjusted to the light. It was a social studies room, as evidenced by the globe Charlie had knocked to the floor. And it seemed they had plans to watch a movie today. The shades were drawn and the projector was set up and ready to go. The door to the hallway was cracked open just an inch, but Marcus rushed to close it before any zombies could sneak in and join us.

Charlie pulled up one of the shades and stared outside. “You guys, I think there’s only one classroom left. We’re almost at the end of the building.”

Willa took an elastic out of her pocket and pulled her hair up into a tight bun. “The next room is my health class. If that room is empty, too, and we can be quiet,”—she cut her eyes to Charlie and the globe he’d crashed into, “then it will be clear sailing. There’s an exit in the hall right outside that classroom.”

I took a deep breath. “I’ll go first this time.” Both Marcus and Charlie had taken turns leading the way. It was only fair. Terrifying, but fair.

I leaned my ear up against the door like they had done, but all I could hear was my own heart pounding loudly in my chest . . . and in my ears and my throat. I mean, was my heart traveling throughout my body? Did I suddenly have several hearts?

No more procrastinating, I told myself. Just do it. The room would be empty, like the others. I’d gotten myself so worked up that my hand was sweaty and slick. It took me a couple of tries to turn the knob, then I let the door sway inward.

Willa was right; it was the health room. There was an illustration of a uterus on the board, which I didn’t really need to see at that moment, and posters reminding us to eat our vegetables and to exercise. No lights were on, but the shades were up, giving the room a dim yellow glow. The coast seemed to be clear, so I inched inside. The only other place left to look was behind the door, so I poked my head around it . . . and screamed.

I fell backward onto my butt in the middle of the room. The boys rushed in after me, with Willa close behind, holding her ruler over her shoulder like a baseball bat. But then they started laughing. Like, doubled-over, can’t catch your breath laughing. And I realized what I had done.

I’d screamed at a fake skeleton.

“That’s Fred,” Willa said between gasps of laughter. “He’s made of plastic.”

And I could see that now. “Fred” was a fake skeleton used for health class instruction. He even had a metal pole and stand keeping him upright.

“Okay, okay,” I said. “You guys can stop laughing at me now.”

“But,” Charlie choked out, “you should have seen your face. You fell down!”

Marcus was backing toward the hall door, still laughing. “You screamed so loud! It was hilarious.”

Every cell in my body froze. The door to the hall was open. Just a crack, but open. And we’d been so loud. We could have certainly attracted some zombie attention.

I held a hand up. “Marcus! The door!”

But as soon as the words left my mouth, Ms. Happel lumbered through it and chomped her teeth down on Marcus’s shoulder.

He cried out in pain, his eyes widening in shock and then realization. He knew he was done for. He’d turn into a zombie any moment now. And he’d bite us next.

So he pushed Ms. Happel out into the hall and followed her. And with one last glance back at us, he closed the classroom door, saving us from what he was about to become.