There exist three laws of robotics: the first that robots cannot injure a human being or allow a human to be injured through inaction, the second that robots must obey orders given to them by human beings except where the orders conflict with the first law, and the third that a robot must protect its own existence provided that its own protection does not conflict with the first or second laws. In the year 2015, engineers Greg Powell and Mike Donovan are stationed at a ten-year-old abandoned mining base on Mercury. They find out that the photocell banks that provide life support to the base are short on selenium and are about to fail. Without the selenium, it will be difficult to maintain their climate control systems and they will burn to death. They send Robot SPD-13, known as Speedy, to go fetch selenium (the nearest pool is seventeen miles away), as Speedy can withstand Mercury's high temperatures. After five hours, Speedy still hasn't returned, worrying Powell and Donovan. They decide to travel through tunnels under Mercury's surface, limiting their exposure to the heat and radiation of the planet's "Sunside." When Powell and Donovan find Speedy, they find him running in huge circles around a selenium pool, walking with a lurching and staggering gait, and talking oddly and singing to himself. Donovan notices that it looks like Speedy is drunk. Since a robot cannot be drunk, Powell concludes that Speedy's strange behavior is because of a conflict among the three laws of robotics. In approaching the pool, Speedy obeys the engineers' orders but since he is putting himself in danger, he retreats, and thus continues his feedback loop and oscillation around the pool. Powell and Donovan try a few things to break Speedy's cycle, first by creating dangerous concentrations of carbon monoxide, forcing Speedy away from the pool and out of equilibrium. This plan backfires. Speedy backs away until the gas dissipates and then resumes his orbit around the pool. As time is running out, Powell realizes that he could probably break Speedy's cycle by invoking the first law of robotics: that a robot cannot allow a human being to come into harm. He steps towards the pool himself and flags down Speedy to come rescue him, which works-- Speedy snaps out of his drunken state and carries the heat-stricken Powell back to safety.