Ross Sylibus is a Chicago cop, who lost his partner in a battle with a cyborg. He has just been transferred to Mars as an expert on androids, but before he has even left the spaceport he spots a group of suspicious people, who turn out to be a madman with cyborg bodyguards. With the help of his soon-to-be partner waiting in the terminal, Naomi Armitage, he stops the cyborgs, but their leader escapes. The plot thickens when they find out that the group was carrying the body of a android, a very popular country singer, impersonating a human. At the MPD office, Ross and Armitage are paired up in the investigation of this unusual crime. As it turns out, someone is murdering androids — the rare and illegal Third Types, nearly indistinguishable from humans — who have been living undetected as humans. Ross is already uncomfortable with the investigation, and when he finds out that Armitage herself is a Third, he does not know what to make of the situation. Matters are further complicated when he is severely injured in a confrontation with the android assassin, and has to have large parts of his own body replaced with cybernetics. All the while, the threat of war with Earth looms overhead, and these crimes appear to be related somehow. Armitage becomes a wanted android, and Ross must choose between her and his prejudices.