Crewmember Seven of Nine and Ensign Tom Paris have returned to Voyager from an away mission with young Naomi Wildman to learn the crew believes they have found a wormhole leading directly back to Earth. Seven is immediately suspicious, and reviews Captain Kathryn Janeway's logs since their departure. Janeway's earlier logs indicate what they had found was a wormhole but was giving off deceptive readings; the later logs appear to dismiss those concerns, with Janeway directing the ship towards it without concern, believing to have obtained communications from Starfleet directing them through it.
Seven continues to try to investigate the wormhole, but the ship's crew deny her the resources to do so; the astrometrics lab is taken offline to conserve power, and her communications with an alien Qatai, warning them not to go into the anomaly, is cut short. Seven talks to Naomi, and realizes that they are the only two that do not seem to be enthralled with returning to Earth, as Seven cannot remember Earth and Naomi has never seen it. Suspecting something is influencing the crew, Seven discusses the problem with the computer-generated Doctor, who agrees with Seven's assessment. Before he can investigate, the crew take the Doctor offline, and attempt to place Seven into stasis, believing it will prevent attracting the Borg with their passage. Seven tries to evade the effort and stop the ship, but the crew fights back, eventually sending a surge of energy to knock Seven out.
Seven wakes to find that Voyager has entered the anomaly, and stopped dead inside what appears to be a gigantic bio-organism digesting the ship's hull. The remaining crew have been knocked unconscious. Seven makes contact with Qatai, whose ship is also trapped inside the anomaly. Qatai reveals that they are inside a creature that consumes starships by telepathically tricking their crews into their hearts' desires, and altering their sensor readings. He had been trying to destroy the creature for years after it had killed his wife and family. After reactivating the Doctor, he, Seven, and Qatai come up with a plan to force the creature to eject both ships by igniting some of Voyager's antimatter with Qatai's weapons. They execute the plan, and it appears to be effective, both ships free of the creature, but Qatai asserts they are still inside the creature, and that their escape is what Seven desired and the creature is still influencing her. They repeat the procedure, and convince themselves they have fully ejected themselves from it.
As Voyager returns to consciousness and set course to the Alpha Quadrant, Qatai is seen returning to the creature. It remains unclear whether Qatai is intent on destroying it or simply returning to a life of delusional captivity.