Neelix tells a story, while trapped with the ex-Borg children during a power outage aboard the USS Voyager, a Starfleet vessel stranded on the opposite side of the galaxy.
This story allegedly takes place a short period before the Borg children had come aboard the ship, so they do not know if it is true.
Through various circumstances, apparently thrown in by Neelix to add tension to the story, several suspenseful situations arise: Ensign Kim and a female crewman become the only two on several abandoned decks, Tom Paris is brutally injured by an electric discharge from his console, the Doctor goes offline, and Tuvok and Neelix must get to safety by themselves.
In Engineering, Janeway plays a hunch and talks to what was previously assumed to be a communication malfunction, but is in fact the entity trying to speak.
Eventually, Janeway is able to talk to the entity, and realizes that the malfunctioning systems have been its attempt to return to the nebula where it lived.
The Captain informs him that they are taking some final readings before resuming course, and shows him an image of the nebula on the viewscreen.
[1] Den of Geek ranked this 21st among episodes with a Bryan Fuller writing credit, in this case he worked on the teleplay.