Another Gregory Powell and Mike Donovan story. This is the first story to feature explicitly the Three Laws of Robotics:
- A robot may not injure a human being or, through inaction, allow a human being to come to harm.
- A robot must obey the orders given to it by human beings, except where such orders would conflict with the First Law.
- A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
A robot named Speedy, sent away to collect selenium on Mercury, has been absent for five hours. Powell and Donovan have to figure out why. Because the selenium pool presents a danger to the robot, the robot is conflicted between the second and third laws. While the second precedes the third, the command was not strongly worded so that the robot is driven to insanity.