Tin wanders forlornly through the huge laboratory complex of the Metal Men. Tin's creator, Will Magnus, as well as the other Metal Men, all seemingly lead fuller lives than the little Tin robot. Wandering into town, the lonely Tin purchases a "do-it-yourself" robot kit, and builds himself a tin companion. The robot "girl" is brought to "life" using one of Magnus' responsometers, the integral design component of all the Metal Men. The joyful Tin shows off his new girlfriend/companion to his fellow Metal Men, to the immediate derision of Mercury. When Platinum chastises Mercury for ridiculing a teammate, a miner scrap breaks out, angering Will Magnus. For causing such dissent between the Metal Men, Tin's robot companion runs off, with Tin in pursuit. Reaching the Metal Men's jetaway, Tin's girlfriend takes off, setting a course away from Earth.
Tin molds himself into a boomerang, and, with an assist from Iron, reaches the jetaway on Iron's second throw. Magnus opens a communications link to the jetaway and pleads with Tin to return to base. The two tin robots, however, decide to find a new world where they will no longer cause trouble for the Metal Men. Despite repeated pleas from Magnus, and all the Metal Men, to come home, Tin turns a deaf ear to his former friends. He continues to pilot the jetaway deeper into uncharted space. Eventually, Tin discovers a series of planetoids, all covered in the ruins of seemingly terrestrial cities. The cities themselves are devoid of organic life, but are infested with a kind of robot termite that feeds on the base elements of the abandoned structures. Each planetoid hosts a progressively worse infestation.
On the final planetoid, the two tin robots encounter a a skyscraper devouring robot that has grown as large as the very buildings it consumes. Spying the two tin robots, the giant machine gives chase. Tin and his companion are barely able to make it back to the jetaway. Blasting off back into orbit. they are horrified to discover that the final planetoid is, itself, capable of controlled space travel. It's destination, Earth. Breaking radio silence, Tin tries to warn his fellow Metal Men of the approaching threat, to no avail. Magnus dismisses Tin's wild claims, just as the skyscraper sized robot lands on Earth. It's foot just grazes Magnus' car, crushing it utterly. Magnus is rendered unconscious in the accident, and the Metal Men see no easy way to remove him from the crumpled remains of his car.
Fearing for Magnus' safety, the Metal Men spring into action against the structure devouring, machine menace. While Lead forms a shield around Magnus' car, to protect him, the other Metal Men manage to topple the giant robot, if only for a moment. Converting their forms into hammers, Gold, Lead, and Iron pummel the robot, searching for a weak point to exploit. When the two tin robots finally arrive back on Earth, Gold has them coat Iron's hammer form. With Iron now covered in a protective tin coating, Lead begins furiously hammering away at the robot, until it finally breaks down. The two tin robots bend themselves into the shape of a giant can opener, which Lead uses to free Magnus. Back at their base, the Metal Men give a proper welcome to Tin's robot companion, at which point Tin realizes he has yet to give his creation a name. Magnus and the Metal Men break the fourth wall, asking the readership to write in with suggestions for naming Tin's girlfriend/companion.