"As if he'd found something that scared him," Tom said, "or something that he didn't understand. He was afraid to tell anybody. And whatever he found, he managed to hide it somewhere, so that nobody would find it...."

"Then why didn't he hide this part of it, too?" Greg said.

"Maybe to be sure there was some trace left, if anything happened to him," Tom said.

They were silent for a moment. The only sound was the stertorous breathing of the unconscious guard. "Well," Greg said finally, "I have to admit it makes sense. It makes other things add up better, too. Dad was no fool, he must have known that Tawney was onto something. And Dad would never have risked his life for an ore strike. He'd either have made a deal with Tawney or let him hijack the lode, if that was all there was to it. But there's still one big question ... where did he hide what he found? And we aren't going to find the answer here." He walked over to the hole in the wall.

"Made quite a mess of it, didn't it?" Johnny said.

"Looks like it. I wonder what that thing would do to a ship's generator plant." He turned to Johnny. "We haven't much time. With this thing, we could tear this ship apart, leave them so confused they'll never know what broke loose. And if we could get that gun back to Major Briarton, he'd have to listen to us, and get the U.N. Patrol into the search...."

They had been so intent on their talking that they did not hear the footsteps in the corridor until the door swung open. It was another guard, the one who had departed with Tawney. He stopped short, blinking at his companion on the floor, and then at the gaping hole in the wall. When he saw the twins, side by side, his jaw sagged and a strangled sound came from his throat.

Then Johnny grabbed his arm, jerked him into the lounge, and slammed the hatch shut. Greg pulled the stunner from his holster and tossed it to Tom. The guard let out a roar, twisted free, and met Johnny's fist as he came around. He sagged at the knees and slid to the floor beside the other guard. "All right," Johnny said, "we've dealt the cards, now we'd better play the hand. Tom, you first."

Tom pulled the ventilator grill down, and climbed up into the shaft. Greg followed, with Johnny at his heels, pulling the grill back up into place from the inside. They waited for a moment, but there was no sound from the lounge.

"All right," Johnny said breathlessly. "Let's move."