Kes and the Doctor notice a peculiar change in the remains of the Caretaker, the alien who trapped Voyager in the Delta Quadrant. They seem to be resonating in response to an unusual energy source. Remembering that the dying Caretaker had mentioned a female of its kind, Janeway wonders if she could be nearby. If so, a meeting with her could be their ticket home. As a precaution, Tuvok develops a toxin that could debilitate the female lifeform if she poses a threat. Following the energy trail, the crew comes upon a space station inhabited by Ocampa, who fire on the ship.
Kes agrees to act as the crew's liaison to her people, and when the Ocampa leader, Tanis, boards Voyager, she assures him that the crew comes in peace. In a private meeting, Tanis tells Kes that the female caretaker, Suspiria, is nearby. She has taken care of this group of Ocampa for 300 years, and has taught them to develop their psychokinetic skills. He shows Kes a sample of the powerful abilities she has yet to tap. Later, Tanis communicates with Suspiria, who demands that he deliver Voyager to her.
As Tanis leads the crew to Suspiria, he tutors Kes on her telepathic skills. The lessons nearly end in disaster when Kes tries to boil water with her mind and, to her horror, inadvertently boils Tuvok's blood instead. He collapses, writhing in agony.
Fortunately, Tuvok recovers from the near-fatal incident. Kes realizes the full potential of her mental powers when her mind causes the plants in the airponics bay to burn up. Tanis urges Kes to leave Voyager and live on the Ocampa space station, where he says she will be embraced by Suspiria and surrounded by her own people.
Suspiria comes aboard the ship and tells Janeway that she will destroy Voyager in retaliation for the crew's part in the Caretaker's death. Suspiria attacks several officers and is ready to complete her mission of revenge when Kes becomes aware of the monstrous plot. Kes attacks Tanis with her expanded psychic abilities, and Tanis' pain temporarily incapacitates Suspiria. Janeway is then able to fire the toxin, subduing her. Janeway allows Suspiria and Tanis to leave the ship, while Kes remains with her friends on Voyager.