In this episode, Captain Picard finds himself abducted from the Enterprise and held in a chamber with other prisoners, while a doppelgänger replacing him behaves strangely and gives increasingly disturbing orders.
Captain Picard, while sleeping in his quarters on the Enterprise after the successful completion of a mission, is abducted by an unknown device and finds himself in a cell with two other prisoners: StarfleetCadet Haro from Bolarus IX and philosopher Kovar Tholl from Mizar II. They are later joined by the violent Esoqq from Chalnoth. While they have meager beds and facilities, their only source of nutrition is provided by a tasteless rubbery disk, which Esoqq is unable to eat. He moves toward Tholl but Picard is able to dissuade him temporarily. Picard attempts to learn why the four of them have been abducted but can find no connection. Picard organizes Haro and Esoqq to attempt to break the lock on the only door to the cell. Initially foiled by a stun beam when they tamper with the controls, they manage to override the beam and then defeat the door's security, only to find a blank wall behind it.
Meanwhile, on the Enterprise, a doppelgänger of Picard has taken his place, ordering the ship to delay a scheduled rendezvous with another ship and travel slowly at warp two to a nearby pulsar. En route, Picard's double exhibits behavior that the senior crew begins to question, such as his newfound romance for Dr. Crusher or engaging the crew in singing Heart of Oak, the official march of the Royal Navy, in Ten Forward. When, upon arrival at the pulsar, Picard's double orders the ship closer which would expose the crew to lethal radiation, Commander Riker and the rest of the bridge crew refuse to follow his orders and mutiny.
The real Picard, after discovering the false door, deduces that Cadet Haro is not who she claims to be due to her knowledge of classified details. The four different alien captives and the tightly controlled setting are suggestive of some kind of experiment: Tholl (the collaborator who goes along with whomever's in charge), Esoqq (typical for his species, a violent anarchist who rejects any kind of authority), Haro (the cadet, sworn to obey orders without question), and Picard (the leader, accustomed to giving orders). Haro reveals herself to be an alien species, and that he and his comrades were studying the concept of authority. The aliens quickly return Picard and the other captives to their respective locations. On the Enterprise, Picard's double is also revealed to be of the same alien species. Before the aliens can leave the Enterprise, Picard orders a force field to hold them, and then, after seeing how they react to being ensnared, allows the aliens to go free, warning them not to abduct others again.