Kes' mind is taken over by a tyrant.
Voyager rescues three Ilari from a damaged ship, but the injured Tieran dies in sickbay. Soon afterwards Kes abruptly ends her relationship with Neelix, then kills an Ilari envoy and a crewman and escapes in a stolen shuttle with the two other survivors. Tieran, a ruler overthrown two centuries earlier who has lived on by moving his mind from host to host, has taken over her body and means to use her telekinetic power to retake his world.
On Ilari, Tieran murders the ruling Autarch and claims the title, while Janeway sides with Demmas, the rightful heir. Tuvok is captured but reaches Kes through a mind meld, and she fights Tieran from within until the crew can separate and destroy him. Demmas becomes Autarch. The third-season episode shows Kes's growing mental strength and hints at the changes that will soon take her away from Voyager and from Neelix.