Mr. Heindecker ran to Jake’s aid. He yanked the rat from the boy’s hand and threw the animal hard to the ground, where it hit with a splat and lay still. At the sight of Jake’s bleeding hand, Valerie leaned forward, put her hands on her knees, and threw up everywhere.

Amy watched as, the lid removed, the other three rats leapt out of their cage and went darting through the room, making horrible shrieking noises as they went. The room came alive with panic, the air full of screaming kids, yelling parents, and Jake’s sobs. Amy felt her face go cold and sweaty as the entire science fair erupted in full-blown panic. People shoved one another out of the way, knocking over young kids. Projects were toppled, volcanoes spewing vinegar and baking soda all over people’s clothing, wires sizzling as potatoes were mashed underfoot. Dad had lifted Katie high from the floor while Mom immediately looked for the nearest exit.

As Amy watched, one rat started bolting in their direction, squealing at the top of its lungs. It seemed to be beelining right toward Amy—when Rover stepped between them. The frantic rodent stopped its headlong rush as if it had been hit with an electric shock. It sat up and trembled, looking into Rover’s calm gaze with its own bright, beady little eyes. Then it fell over, perfectly still, blood spilling from its mouth and pooling around its head.

Amy couldn’t believe something this horrible could happen at the science fair. It was like she was in a dream—a terrible dream full of blood, and horror, and …

Something touched her hand.

Amy looked down to see Rover at her side. The dog had the end of his leash in his mouth, offering it to her.

Chapter 10: Natural Enemies

She was riffling through her backpack when she heard the click. The sound made her freeze, seemed to silence all other sounds in the room. She swallowed dryly and forced herself to find her social studies workbook before she stood and walked to the door.

Amy tried the knob. The door swung open. It was unlocked.

She’d locked it a few minutes ago. She could’ve sworn she’d locked it.

She threw the lock again, grabbed her workbook, and stormed toward her desk, determined to get some work done—

Click.

She froze. There, again, for the hundredth time in the past two days since the science fair. She considered trying to ignore it, to tell herself it was just some noise in the house, the pipes adjusting or some nonsense like that. But she hated the idea of just leaving it unlocked, of letting him get his way.

She turned, stomped back, locked the door again. “Stop it,” she said softly, and turned back to her desk.

Click.

“Oh, come on,” she snapped, turned back around—and shrieked.