The U.S.S. Enterprise is assigned to escort a young girl and her guardian from the planet Klavdia III, where they have lived almost all of the girl's life, to Daled IV, the planet she was born to rule.

The sixteen-year-old Salia has a chance encounter with Wesley Crusher, who is instantly and obviously smitten with her, much to the dismay of the girl's overprotective guardian Anya. After a short lesson in love from Guinan and Riker, a nervous Wesley calls on Salia in her quarters, where he introduces her to Thalian chocolate mousse. All the while, Troi is concerned that the emotions she senses from the new passengers don't seem to fit who they are.

Meanwhile, during a tour of sickbay, Anya discovers that there's a contagious patient on board and insists that he be killed immediately. When no action is taken, Anya becomes a raging monster intent on murdering the patient herself. Worf is barely able to fight off the monster before security arrives. Dr. Pulaski suspects that the passengers are allasomorphs, a species rumored to possess the power to change into other life forms. In order not to provoke Anya further, Picard orders Wesley to stay away from Salia.

Disobeying Anya's wishes, Salia sneaks into Wesley's room where she exchanges a passionate kiss with the smitten ensign. When the angry monster suddenly appears, Salia herself transforms into an even more frightening creature, resulting in a tense stand-off between the girl and her guardian. After they change back to their humanoid forms, Wesley is left stunned at the discovery that the girl of his dreams is not who he thinks she is.

Nearing the end of her stay, Salia tries to apologize to Wesley for any pain she may have caused him, but her pleas are met with indifference. Telling Wesley that she loves him, Salia heads toward the transporter room. When Wesley realizes his true feelings, he bursts into the transporter room bearing a bowl of Thalian chocolate mousse just as Salia is about to be beamed down to Daled IV. The two share a last taste and a last embrace before Salia bids Wesley a fond farewell.