They climbed back up the tunnel and Donovan looked through the hole. "I can see them! They're marching. No, wait a minute. They're dancingt ey're dancing towards us! "I hope they come near enough. Dave can sense our presence at six metres. How near are they now?' "Fifteen metres. We'll be out in fifteen minutes. Oh, no!' 'What? Let me look!' shouted Powell. "They've turned! They're leaving! Powell shook Donovan. "Mike! Listen, I've got an idea! Let me get in there before they move too far away! Donovan slid down. "Hey! What are you going to do with that gun?' He held on to Powell's arm. Powell shook him off violently. "Let me get in there!' He aimed his gun carefully through the hole at one of the robots, and then fired. He brought the gun down and stared anxiously along the tunnel. One of the subsidiaries was down! Powell called uneasily into his radio. "Dave? There was a pause, and then both men heard the answer. "Boss? Where are you? My third"finger" has been destroyed. Leave your subsidiary. We're trapped down here. Can you see the light from our torches?" "Yes. We'll be with you in a few minutes. Powell dropped on to the floor. "It's all over!" he said thankfully. "All right, Greg,' Donovan said softly. You win, and I'm just stupid. Now tell me all about it. Easy. We missed the obvious fact. We knew it was a