The Enterprise brings aboard the Betazoid Federation emissary Tam Elbrun, and takes him to a distant star system. Elbrun, whom Deanna Troi previously knew when he was a mental patient, has a history of mental instability due to his overpoweringly strong telepathic capabilities, gained much earlier than most Betazoids, but his unique skills are used for first contact situations with alien life. On this particular mission, Elbrun's abilities are needed to try to coax a giant sentient spaceship, nicknamed "Tin Man" away from a star that is about to go supernova. En route, Elbrun finds it impossible to filter out the thoughts of the Enterprise crew, but when meeting Data, he is puzzled by finding what he calls 'absence of mind', but also finds relief in developing a friendship with Data, who, being an artificial lifeform, has no thoughts to be read.
When they arrive, the Enterprise is attacked by a Romulan Warbird waiting for them. The warbird turns to attack "Tin Man", but Elbrun sends it a telepathic warning. "Tin Man" emits an energy wave that destroys the Warbird and seriously damages the Enterprise. Elbrun, now in communication with "Tin Man," reveals that it calls itself Gomtuu. Gomtuu has existed for many millennia, is possibly from another galaxy, and used to have a crew, but they were lost in a radiation accident; due to combination of remorse (feeling responsible for the loss of the crew), loneliness (having no crew), and a feeling of uselessness (again, having no crew, no purpose), Gomtuu wishes to die in the supernova. Elbrun requests to be beamed aboard the ship but Picard is cautious of this action. When a second warbird arrives, Picard lets Elbrun transport to Gomtuu along with Data to help protect the ship. Elbrun is initially overwhelmed with data from Gomtuu but eventually comes to identify himself with the ship. With the supernova imminent, the elated Elbrun informs Data he will stay with Gomtuu, believing it is where he truly belongs.
Gomtuu leaves the star's orbit moments before the start of the supernova, and sends the Enterprise and the Warbird spinning out of the star system in separate directions before they are caught in the solar blast. As the Enterprise regains control they find Data aboard the bridge, who reports what happened aboard Gomtuu. Later, when Data discusses the events with Troi, Data comes to realize that like Elbrun with Gomtuu, the Enterprise is where he belongs.
The story originated as a spec script submitted by Dennis Russell Bailey (under the name Dennis Putman Bailey), David Bischoff and Lisa Putman White. "Tin Man" was based on a 1970s short story "Tin Woodman" and later novel (Tin WoodmanISBN 0-385-12785-5) cowritten by Bailey and Bischoff. The short story had been nominated for a Nebula Award in 1977.
Rick Sternbach and Greg Jein's design for Gomtuu was inspired by the thermal pods in Buckaroo Banzai.