Among the Enemy by Margaret Peterson Haddix

first, just to see."
Matthias suspected she was trying to protect him, in case Percy and Alia hadn't survived the hours he'd been away.
"No," he said quickly, picking up a flashlight. "You'll need me to show you how to open the trapdoor."
    Mrs. Talbot didn't object. They both got out of the car, and the chilly night air was all Matthias needed to come fully awake.
    "Don't look at the bloodstains," he told Mrs. Talbot as they stepped through the shattered doorway into the cabin.
"I've seen blood before," Mrs. Talbot said.
    The circle of the flashlight's glow was eerie against the plank floor because of the blood and the shadows of all the cracks. Matthias was eager to get down to the secret room and the lantern's cozy light. He found the latch quickly and lifted the trapdoor.
"Percy? Alia?" he called softly. "I got help, just like I promised."
    The lantern had gone out, but that didn't faze him. He climbed down the ladder and pointed his flashlight upward so Mrs. Talbot could see to climb down as well. Then he turned the light toward the cots. The glow was so feeble that it didn't penetrate very far into the darkness. He couldn't see.... He stepped closer. He could make out the frames of the cots, the blankets piled on top of them— the empty cots, the folded blankets.
Percy and Alia were gone.

    Chapter Thirteen
    Where are they?" Mrs. Talbot asked, looking around. \- ', She didn't understand that they were missing. Matthias couldn't understand either. He whipped the flashlight all around, and its glow shot crazily from one side of the room to the other. Maybe Percy and Alia had crawled off their cots to go to the bathroom and then fainted before they could get back. . . . Maybe that might have happened to one of them, but both?
Neither of them was huddled anywhere on the secret room's dirt floor. They'd vanished completely.
Matthias raced back up the ladder. Maybe they were in the cabin itself....
He repeated his routine of flashing the light all around the room. The upturned chairs made shadows big enough to hide behind, so he kept getting glimmers of hope— hope that died instantly when he moved the chairs aside and saw nothing there. He scrambled to the door of the cabin.
"Percy? Alia?" he shouted hoarsely into the dark night. "Where are you?"
    Mrs. Talbot grabbed his arm just as he started to step outside to search for them.
'Are you out of your mind?" she asked, her eyes blazing. 'Are you trying to find them or get us killed?"
If he couldn't find Percy and Alia, it would be like dying.
    "They were here," he said furiously. "What could have happened to them? I never should have left them. This is all my fault. It's my fault Percy got shot—the Population Police must have heard him answering me. It's my fault Alia got hurt—oh, why didn't I think before I tried to stop that truck? Why didn't I—?"
"Stop it," Mrs. Talbot said, taking him by the shoulders and shaking him. "Hysteria never helped anyone. We can look for them, we can find them if you'll just calm down."
"Somebody took them away," Matthias moaned.
"Yes, probably," Mrs. Talbot agreed. "From your description of their injuries, I don't think they could have walked out of here on their own. We just need to figure out who took them and why.... I know. You go back down into the basement and see if there are any secret routes out that you missed before. I'll go outside and look for footprints."
Matthias had searched the underground room as thoroughly as possible the night before, so he didn't think much of Mrs. Talbot's suggestion. But he didn't say so. He sat numbly until she was out the door. Then he sneaked over and watched her.
    She kept her flashlight trained on the ground for only a few moments. Then, when she reached the pile of dead bodies, she pointed the light straight at it.
She believes Percy and Alia might be dead, Matthias thought, so jarred by the thought that he staggered back- ward. She thinks someone just threw their bodies on the pile with the