During a romantic respite on Risa, Riker's lady friend Etana Jol gives him an interesting present. She introduces him to an electronic mind game that rewards the player with a pleasurable sensation when he achieves his goal. Eager to share his discovery, Riker passes the game on to Troi when he returns to the U.S.S. Enterprise. At the same time, the crew happily welcomes Wesley Crusher, who is on vacation from Starfleet Academy, with a surprise party. Troi introduces Beverly to the game, while Wesley meets a young ensign named Robin Lefler. He feels an immediate chemistry with the attractive young woman, and Robin is also drawn to Wesley. Soon, the two young people make plans to meet for dinner. A short time later, Beverly summons Data to Sickbay to help with a problem. But when the android arrives, Beverly, Riker and Troi inexplicably attack and deactivate him, laying him on an examination table.
Beverly asks Picard and La Forge to come to Sickbay, ostensibly to help with Data. But when they arrive, she, Riker and Troi lie about what happened, claiming that the android just collapsed. Picard leaves Data in the group's hands, and Riker is able to convince Geordi that Dr. Crusher can take care of Data. He then introduces Geordi to the game. Afterwards, Wesley goes to meet his mother in her quarters and finds her engrossed in the game. She invites him to play, and when he refuses, she becomes more insistent. He and Robin talk about it at dinner, and Robin tells him that the game's popularity is increasing. She and Wesley decide to find out what all the fuss is about by hooking the game up to a computer. After disassembling its parts, they are shocked to discover that the game has chemical affects on the brain that cause the player to become physiologically addicted and interrupts higher reasoning processes. Wesley rushes to fill Picard in on his discovery, unaware that the Captain has already fallen victim.
Wesley and Robin soon realize that Data's malfunction coincided with the game's introduction. They examine the android, discover that he has been tampered with and attempt to repair him. Wesley tells Robin that Beverly and Geordi are the only crew members who know enough about Data to have damaged him in this way. Since Data is the only crew member immune to the game's affects, they begin to wonder if Data was deactivated for a reason, and if the game has a purpose other than fun. With horror, they realize that they may be the only people on the board who aren't already addicted. They decide to pretend to play the game in order to fool the rest of the crew.
Back on the bridge, Picard and the crew meet with Etana, the alien woman who first gave Riker the game. She instructs them to distribute the game to another vessel, and the crew readily agrees with her plan to take over the Federation. Soon afterward, Wesley barely escapes when Riker and Worf try to force him to play the game. He goes into hiding, but Robin is not so lucky, and after being forced to play the game, helps the rest of the crew locate Wesley. Just as they force him to play, Data appears and reverses the game's affect on the crew. With the Enterprise out of danger, Wesley bids his friends farewell and returns to the Academy.