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 commit mutiny, according to Starfleet's Directives when the commanding officer shows to be unfit for command.
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. Picard observes that the four different alien captives and the tightly controlled setting are suggestive of some kind of experiment: Tholl, the collaborator who goes along with whoever'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, a leader, accustomed to giving orders. Haro reveals herself to be not a Bolian, but of an unidentified alien species, two of whom appear before the captives. These aliens explain that they were studying the concept of authority and leadership, as their race lacks hierarchical authority structures as humans and other races do. Because the captives' knowledge of the experiment has now made it impossible to continue collecting data on their natural behavior, the aliens 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, all members of which are in constant telepathic contact, which the aliens remark is far superior to the "primitive vocal" communication used by the beings aboard the Enterprise. When Picard criticizes them for engaging in kidnapping and assault, the aliens express ignorance of the morality Picard espouses, and indicate that they will need to study this concept further. However, Picard, using a series of nonverbal cues, orders the crew to erect a force field to hold them, causing the aliens to panic, as they indicate that their species cannot bear captivity. Picard expalins that with his "primitive vocal" means of communication, he instructed his crew to hold the aliens because he wishes to conduct an experiment of his own. After a few moments, Picard releases them, pointing out that they now know what it is like to be captured, and, allows the aliens to go free, warning them not to abduct others again.