Gregory Powell and Michael Donovan have been sent to Mercury to prove the viability of mining operations there. To fully set up their station, however, they need selenium to run the power cells, but the robot they’ve sent out to fetch it is not coming back and starting to behave erratically and won’t come near for an examination. It must be caught and fixed quickly or the Donovan and Powell will roast to death when the station’s power fails...

The first Donovan and Powell story in I, Robot—but not the first written—this is remarkable for the first appearance of the Laws of Robotics in a rudamentally form. Like most of the other Donovan and Powell stories, it’s fun but slight— the conflict here is how the pair will solve the erratic behavior of a malfunctioning (?) robot.