Voyager encounters a Borg cube's debris field containing technology called a Vinculum, a device that connects all the drone's minds. The device causes Seven of Nine to exhibit multiple personalities of people she assimilated as a member of the collective, including a Klingon, a Ferengi, a Vulcan, and a human. Soon, they become so strong that they may overwhelm Seven's own personality.

The crew of Voyager discovers a strange ocean world in space and offers to help the inhabitants find out why the ocean is losing water to space. They find the forcefield maintaining the planet's integrity is breaking down. Tom Paris directly disobeys orders in an attempt to save the planet, which results in his demotion to Ensign and being placed in the brig for thirty days. Paris tells the story of this episode in a letter for his father to pass the time in the ship's brig. When first encountering the world, Paris interrupts Kim in the middle of his Chaotica holodeck adventure.