Riker returns from a vacation on Risa with a game that he is eager to share with the crew. Unfortunately, the game is psychologically addictive (making the crew suffer from Virtual Reality Addiction), and it quickly turns virtually every member of the Enterprise's crew into a mind-controlled pawn of the Ktarians, who are using the devices to gain control of Starfleet. After Data (who, as an android, is unaffected by the game) inexplicably is "incapacitated", only visiting Starfleet Academy cadet Wesley Crusher and young engineering ensign Robin Lefler stand in the way of the insidious scheme.

The episode opens with William Riker visiting Risa and being introduced to a video game by Etana Jol, a Ktarian woman with whom he has become romantically involved during his vacation on the pleasure planet. Riker, upon his return to the Enterprise, distributes replicated copies of the game to the crew of the starship.

Cadet Wesley Crusher, on vacation from Starfleet Academy, is visiting the Enterprise and notices everyone playing the game (and trying to convince him to play as well). Doctor Beverly Crusher, Wesley's mother, secretly switches off Lieutenant Commander Data and sabotages his circuits, because he would be immune to the game's addictive properties—namely, the game's ability to addict people who play it by stimulating the pleasure centers of their brains when they successfully complete each level.

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