After discovering that part of space has mysteriously changed, Voyager gets caught in a struggle involving a weapon capable of altering history. Captain Janeway grapples with the safety of her crew against this powerful threat. While taking refuge in a nebula, the crew works to repair critical malfunctions. Chakotay and Tom Paris, isolated and interrogated by the alien Annorax, learn about his ability to change historical events. Annorax, obsessed with restoring his lost past, including his wife, refuses to cease his mission despite its catastrophic consequences. Janeway forms a coalition to attack Annorax's ship, resulting in a fierce battle that leads to the weapon ship's destruction and the restoration of the original timeline. The crew of Voyager, unaware of these events, proceeds with their journey.