Doc dropped his postprandial cigarette into the disposal slot and came to his feet.

"On your feet, Fly-boy," he ordered. "Plenty workee, so chop chop, up and at it."

"Slave driver," sneered Jon. He squirmed into his antirad suit. He poised the helmet and fired his blast. "I gotta sweat my head off, back there, and you play with tapes up here. Talk about your men and boys. Hah!" And he dogged down the helmet. He could see Doc's lips moving and grinned pleasantly. He made motions to show that he wasn't hearing a word.

He was still grinning when he undogged the tunnel lock and closed it behind him. Between the double doors, he twisted his body in the cramped space to undog the second door. When it swung open, he had to crawl through the narrow opening into the tunnel. He thrust head and shoulders into the opening, and the weight of the world fell on him. He was jammed against the floor with an unbearable weight, and the threshold of the lock-door was slowly cutting him in two.

"Doc!" he screamed into the mouthpiece in his helmet. "Doc, give me a hand!" Then a cold hand closed over his heart.

The transmitter was off! In his horseplay he had not turned the knob, and now his hands were welded to the floor by the crushing weight.

He lashed out frantically with his lead-soled feet, for they could still move. He tried to pound the lead soles in the distress code, but the pain of his crushed ribs was telegraphing down his nerves and the rhythm was erratic.

Here it comes, he thought bleakly, and a black wave curled over his thoughts.

He caught his breath and gagged. He looked up into Doc's anxious eyes and pulled the mask that was feeding him oxygen off his face.

"Whoosh," he said. "What was that?"