While working to save the planet Tagra IV from environmental collapse due to pollution, the crew welcomes Amanda, a young honor student chosen from hundreds of applicants to serve aboard the U.S.S. Enterprise. The crew is immediately taken with the young woman's boundless enthusiasm. However, Amanda also has a secret she keeps hidden from her new teammates. She possesses extraordinary mental powers, including the ability to make objects appear simply by visualizing them. She manages to keep this power under wraps until she witnesses a potentially devastating explosion in Engineering. With the destruction of the ship imminent, Amanda summons her powers and stops the explosion while the shocked crew looks on.

When the senior staff meets to discuss this turn of events, a surprise visitor arrives to clarify things for them. Q appears out of nowhere in the middle of the meeting with the announcement that Amanda is a Q. He tells the crew that he created the explosion to test the young woman's powers, and, now that he is convinced, he has come to bring her back to the Q Continuum and save her from life as a lowly human. Picard, however, feels that Amanda should make her own decision, and Q reluctantly agrees. Once the two part, Picard secretly orders an investigation into the death of Amanda's natural parents, who were killed in an accident when she was an infant. Despite their agreement, he doesn't trust Q.

Q visits Amanda in her quarters, hoping to tempt her by showing her the range of her limitless powers. Amanda is only interested in seeing her real parents. With Q's help, she visualizes the couple, and they materialize in front of her. The feeling is intoxicating, and suddenly, Amanda is beginning to like being a Q. Confused, she shares her feelings with Beverly, who is unable to offer any real advice. However, when she uses her powers to complete an experiment she was performing for the doctor, Beverly is displeased and chastises Q. In response, he briefly turns Dr. Crusher into a yapping dog.

Amanda can't help being amused by the trick, and begins to test her powers further by playing a game of teleportation hide and seek with her new mentor. Amanda teleports Riker, whom she has a crush on, into her romantic fantasy, but she is disappointed by the artificiality of the result. Meanwhile, Data discovers that the tornado that killed Amanda's parents was very unusual. Picard confronts Q with the information, and he admits that the couple were executed by the Q Continuum — and that he has come to the Enterprise to decide whether Amanda will be executed as well.

Picard and the crew decide to fill Amanda in on this disturbing information. Furious, the young woman summons Q and demands to know what right he has to eliminate others. Picard deftly reminds Q of his supposed moral superiority, but Q lightly replies that he has decided not to kill Amanda anyway. Instead, he offers her a choice. She can either accompany him to the Q Continuum, or continue to live as a human — if she will promise not to use her Q powers. Amanda immediately decides to stay aboard the Enterprise with her new friends. At that moment, however, the group is alerted to an emergency — the planet Tagra IV is in immediate danger of destruction. Realizing that thousands of people will die, Amanda summons her powers and saves the planet, turning it from a polluted no-man's land back to a lush, green world. The event forces her to live up to the fact that she is a Q, and she sadly leaves the ship to start her new life.