Uhura is tormented by hallucinations while the Enterprise helps the USS Farragut repair a deuterium refinery, and she discovers the visions are messages from aliens.
The Enterprise helps the USS Farragut repair a deuterium refinery, and Uhura begins having hallucinations of strange sounds and images, including the deaths of her parents and of Hemmer. Pelia finds that the refinery has been sabotaged, and the saboteur, Saul Ramon, shows the same symptoms as Uhura before trying to destroy the Enterprise and dying in an explosion.
Kirk, serving on the Farragut, saves Uhura and urges her to face her grief. Working with Kirk and his brother Sam, she realizes the visions are messages from beings living in the deuterium who are being killed by the refinery, and Pike has it destroyed. Uhura then introduces Kirk to Spock.