The crew is attacked by an alien using hallucinations.
Voyager is preparing for talks with the Botha, who control the region ahead, and the Doctor orders an exhausted Janeway to rest in her Gothic holonovel. Soon she begins seeing its characters and objects outside the holodeck. Kes can sense the visions too, but the Doctor finds nothing wrong with the captain's brain, and the hallucinations grow more dangerous.
The effect spreads, and crew members fall into a trance as each sees a person or fear from their own mind, including Janeway's fiance Mark. Only Kes and the Doctor are unaffected, and Kes heads to engineering to block the telepathic field, fighting off visions of Tom Paris and Neelix along the way. She succeeds, and a telepathic Botha admits he did it simply because he could, before vanishing. The second-season episode is an early showcase for Kes's psychic strength and for Janeway's Victorian holonovel, a running thread of that season.