The Enterprise is assigned to transport the dauphin, the future ruler of Daled IV, from her planet of voluntary exile where she was tutored and trained by a governess, Anya. The teenage girl, Salia, is the single offspring of the rulers of two opposing factions on Daled IV. Upon the death of her parents, Salia is the sole heir to both sides, making her pivotal to the unification of the warring groups. As such, her governess is extremely protective and suspicious of potential threats to the safety of her charge, and won't permit Salia to leave quarters. However, upon a chance encounter, Wesley Crusher instantly becomes smitten with the girl.
Wesley asks several members of the crew how to talk to a girl, with a particularly amusing scene in which Worf explains how Klingons attract their mates, which involves a humorous combination of females throwing large objects, while males spout love-poetry. Riker and Guinan set the confused Wesley back on track. He calls on Salia at her quarters and introduces her to Thalian chocolate mousse. She confides to him her desire to travel and explore the galaxy as he does, but she can't because of her position. Seeing her distress, he takes her to the holodeck to see different places in the galaxy.
Meanwhile, on a tour of the ship, Anya discovers a patient in sickbay with a possibly contagious disease. Though Dr. Pulaski insists that the ship's containment systems will prevent the disease from spreading, Anya insists that the patient be killed immediately. When the crew refuse, Anya transforms herself into a huge monster to kill the patient herself. Worf intervenes, but Anya is much stronger than he. She desists upon the arrival of Picard. The encounter makes Dr. Pulaski believe she is an Allasomorph: a shape-shifter. Tensions arise between Anya and Worf over Salia's safety, but Worf assures her that because he is responsible for ensuring the security of the ship, he is also in charge of ensuring the security of Salia. Because of the danger she poses to the crew, Anya is confined to quarters and Picard tells Wesley to stay away from Salia.
An Allasomorph in its true form.
Wesley is heartbroken, but Salia sneaks out while Anya is sleeping to visit him in his quarters. When Anya catches them, Salia responds to Anya's monstrous form by transforming herself, to Wesley's shock. Salia tries to explain herself to Wesley, but he feels deceived and repulses her. When they arrive at Salia's homeworld, it is time for Anya and Salia to leave the ship. Anya reveals that she will not be accompanying Salia, but will instead be returning to her home on an orbiting moon. As they say goodbye, Anya says she never meant to hurt Wesley, only scare him. Salia asks Anya if she will ever be able to leave Daled IV, but Anya says it is unlikely. Salia thanks Anya for her upbringing and proclaims she is ready to assume her position as ruler of Daled IV.
Worf escorts Anya to another transporter room to return Anya to her home. Salia thinks she will never see Wesley again, but he hurries to the transporter room to say goodbye and give her a last taste of chocolate mousse. She reverts back into her natural form to beam down through the planet's thick atmosphere, and Wesley is amazed at how beautiful she is.