Summary

Dr. Calvin tells a story of how Donovan and Powell, six months later, found themselves on an asteroid overseeing a new kind of robot, a main robot with six subordinate robots, that worked in the mines on the asteroid. Donovan had noticed that when he was not observing these robots, they would often not return with any ore as they were supposed to do. However, Donovan could not figure out why this was. Powell suggested that they watch the robots through a remote screen called a visiplate, so they could see what the problem might be. After watching for nearly ten days, they could not see one specific thing that was causing the problem, only that the robot seemed to act oddly after dangerous events took place. Finally Donovan and Powell decided to sneak into the tunnels to observe the robots...