The Enterprise arrives at the planet Mintaka III to resupply and repair a Federation outpost being used to monitor the Mintakan people, a proto-Vulcan race near a Bronze Age of cultural development. As the Enterprise assists the outpost, an accident causes the holographic rockface to disappear, exposing the outpost to Liko, a Mintakan; Liko attempts to approach and is hit with an electrical shock, causing Dr. Crusher to transport him to the Enterprise to heal him despite the action violating the Prime Directive. Crusher is able to heal Liko and after wiping his memory of the incident, he is returned to the planet. The crew continue to monitor Liko and discover the mind wipe was not complete as he recalls an image of "the Picard", and has convinced other Mintakans that the Picard is their god.
Riker suggests that he and Troi disguise themselves as Mintakans and to subtly try to dispel the myth of the Picard, while looking for a member of the outpost that has gone missing since the accident. The two are able to find the missing researcher, but are caught by Liko and other Mintakans; while Riker and the injured researcher beam away, Troi is kept under guard. Picard is forced to take steps to rectify the situation without further violation of the Prime Directive. He transports Nuria, the leader of the village where Troi is being held, to the Enterprise and attempts to show her that he and the rest of the crew are mortal, including having her witness the death of a crewman in Sick Bay. Picard returns with Nuria to the surface in the middle of a thunderstorm, which Liko has taken as a sign of the Picard's anger. Nuria attempts to rationalize with Liko, but Liko demands his own proof of Picard's mortality and aims an arrow at Picard. Picard insists that if that is the only proof that Liko will accept, then Liko should shoot. Liko does, but his daughter pushes him so that he only wounds Picard; Nuria shows Liko Picard's blood from the wound, and Liko and the others come to accept that Picard is not a god. Picard and Troi return to the Enterprise, and after he is treated, Picard returns to the surface one last time, and explains to the Mintakans that they will be removing the outpost and allowing them to develop on their own. Before Picard leaves, Nuria gives Picard a sash as a gift.
The sash given to Picard at the end of the episode is seen several times throughout the remainder of the series, hanging from the desk chair in his quarters. It is seen again in the opening ready room scene in Star Trek: First Contact and in several scenes of Star Trek: Insurrection, hanging from the back of his ready room chair on the Enterprise-E.
The title of this episode is a translation of the Latin phrase "Quis custodiet ipsos custodes?" However, the on-screen title did not end in a question mark.
This episode also marks the first appearance of the blue overcoat that Dr. Crusher would wear for the remainder of the series. The overcoat worn by Crusher in the first season (and the first few episodes of the third season) is much more tightly fitted, shorter, had higher pockets and a pronounced collar.
Ray Wise has a guest appearance in this episode. He is best known for playing Leland Palmer, father of Laura Palmer in Twin Peaks. In this episode they hold and protect a character named Palmer.
