Originally published in 1942.
- It's 2015. Gregory Powell and Michael Donovan are on Mercury and they have a problem: they sent out a robot named Speedy to get selenium from a pool and Speedy hasn't come back yet. Which is odd, because he's quite speedy.
- In fact, Speedy is just circling and circling the pool of selenium (22), which is not only odd, but potentially going to lead to Powell and Donovan dying. See, Powell and Donovan need that selenium now in order to fix their "photo-cell banks"—and without those photo-cell banks, their Mercury headquarters is just going to burn up (24).
- (Yay, it's time for an astronomy history lesson: up until 1962, we used to think that Mercury was tidally locked—that is, we thought that one side of Mercury always faced the sun. So we had this idea of Mercury having a sunny side and a dark side, which is a pretty cool image, but not actually true. Still, when Asimov wrote this in the 1940s, that's what he thought, which is why Powell and Donovan need to worry about burning up: their HQ is always in the light. Yay for astronomy history.)
- Powell and Donovan need to get Speedy back, but they can't do it themselves; their inso-suits (insulation suits) will only keep them safe for 20 minutes in the sun (30).
- There are some 10-year old robots lying around from the first (failed) expedition to Mercury. These robots are giant and more primitive than Speedy (for comparison, check out the history of cellphones to see how we got from giant, diesel-operated mobile communication to Angry Birds). But what's worse is that, because they were built at a time when people were afraid of robot rebellion, these old robots will only move if a human is riding them.
- (Powell uses the word "mahout" here, which refers to someone who rides an elephant. Now that you know that word, you can use it in your everyday life.)
- So they can't go out to get Speedy, they can't send a robot, and they still don't know what's wrong with him.
- Powell and Donovan use some tunnels (remember, this is supposed to be a mine) to get closer to Speedy, who is still acting funny.
- (There's an awesome description here of what Mercury might be like, since everything is brighter and darker without atmosphere. Well, as Powell explains, Mercury has a tiny, poisonous atmosphere (86). Notice how Asimov likes to sneak science into his stories?)
- The robot SPD 13, who they call Speedy, is acting drunk: he's wobbling around, going in a circle, and singing Gilbert and Sullivan, which no robot does when sober. In fact, no one does that when they're sober.
- Then Powell and Donovan work out what's going on by thinking about the Three Laws of Robotics:
- "One, a robot may not injure a human being, or, through inaction, allow a human being to come to harm.
- "Two… a robot must obey the orders given it by human beings except where such orders would conflict with the First Law.
- "And three, a robot must protect its own existence as long as such protection does not conflict with the First or Second Laws" (138, 140, 142).
- So here's the answer to the mystery: Speedy is acting drunk because he can't figure out which law to follow. Speedy is an expensive robot, so the Third Law was strengthened—and there's some dangerous gas near the selenium pool. And when Speedy was ordered to get selenium, the order was casual. So Speedy is caught between a weak Second Law (his order) and a strong Third Law (his self-preservation). So Speedy can't go forward to get the selenium (Third Law) and he can't go away because he was ordered to get the selenium (Second Law)—so he just goes around and around in a circle.
- Powell and Donovan try to use a chemical danger to force Speedy to come to them, but that doesn't work because the weak Second Law and the strong Third Law are still in conflict (198-9).
- Powell realizes that the only answer is to bring the First Law into play: a human has to be in danger to snap Speedy out of his drunken stupor.
- So Powell runs out into the sun and tries to get Speedy's attention. Like "hey, I'm going to die unless you stop singing Gilbert and Sullivan!" Which sounds like a typical Thanksgiving to us—please, parents, stop singing.
- One of the older robots almost ruins the plan by trying to save Powell before Speedy can do it, but Speedy saves Powell just in time (228).
- And everyone gets a happy ending: Powell recovers, Speedy gets the selenium from another pool, and Powell and Donovan start planning their next mission—a cool space station will be a nice change after almost burning up on Mercury.