"Canaries," Muller said. He frowned, though he must have known of them. It was traditional to keep them in the engine-room, though the reason behind it had long since been lost. "Better kill them, Mr. Wilcox." Wilcox jerked, and his face paled a bit. Then he nodded. "Yes, sir!" That was when I got scared. The idea that two birds breathing could hurt our chances put things on a little too vivid a basis. Only Lomax seemed unaffected. He shoved back now, and stood up. "Some tests I have to make, Captain. I have an idea that might turn up the killer among us!" I had an idea he was bluffing, but I kept my mouth shut. A bluff was as good as anything else, it seemed. At least, it was better than anything I seemed able to do. I prowled over the ship, sometimes meeting Peters doing the same, but I couldn't find a bit of evidence. The crewmen sat watching with hating eyes. And probably the rest aboard hated and feared us just as much. It wasn't hard to imagine the man who was behind it all deciding to wipe one of us out. My neck got a permanent crimp from keeping one eye behind me. But there wasn't a shred of evidence I could find. In two more days, we began to notice the stuffiness more. My breathing went up enough to notice. Somehow, I couldn't get a full breath. And the third night, I woke up in the middle of my sleep with the feeling something was sitting on my chest; but since I'd taken to sleeping with the light on, I saw that it was just the stuffiness that was bothering me. Maybe most of it had been psychological up until then. But that was the real thing. The nice part of it was that it wouldn't be sudden--we'd have days to get closer and closer to death; and days for each one to realize a little more that every man who wasn't breathing would make it that much easier for the rest of us. I caught myself thinking of it when I saw Bullard or Grundy. * * * * * Then trouble struck again. I was late getting to the scene this time, down by the engine room. Muller and Bill Sanderson were ahead of me, trying to separate Hal Lomax and Grundy, and not doing so well. Lomax brought up a haymaker as I arrived, and started to shout something. But Grundy was out of Muller's grasp, and up, swinging a wrench. It connected with a dull thud, and Lomax hit the floor, unconscious. I picked Grundy up by the collar of his jacket, heaved him around and against a wall, where I could get my hand against his esophagus and start squeezing. His eyeballs popped, and the wrench dropped from his hands. When I get mad enough to act that way, I usually know I'll regret it later. This time it felt good, all the way. But Muller pushed me aside, waiting until Grundy could breathe again. "All right," Muller said. "I hope you've got a good explanation, before I decide what to do with you."