Kes takes the shuttle to a military encampment and takes command of the waiting troops. In the meantime, Janeway meets with Demmas, the Autarch's oldest son, who explains that Kes' body is now inhabited by Tieran, a former Ilarian ruler who was overthrown by Demmas' ancestor 200 years ago. Since then, Tieran has lived on by transferring his mind to a series of host bodies. Janeway agrees to help Demmas stop Kes/Tieran, but before she can, the tyrant has killed the Autarch in front of Demmas' younger brother, Ameron, and appointed himself the new Autarch.

Kes/Tieran tries to poison Ameron's thoughts against Demmas and urges him to cooperate with the new regime. In the meantime, the Doctor designs a synaptic stimulator that will remove Tieran's neural pattern from Kes — if they can get close enough to use it. Tuvok beams into the Autarch's palace, but is caught and imprisoned before he can succeed in the attempt. When Kes/Tieran interrogates Tuvok, the Vulcan is able to initiate a mind-meld and speak directly to Kes, who tells Tuvok she is fighting Tieran for control.

Kes/Tieran orders Voyager to leave orbit, but the stress of the mental battle between Kes and Tieran results in a paranoid Kes/Tieran killing Adin. To Nori's chagrin, Kes/Tieran announces she's marrying Ameron. Moments later, a coalition of Voyager's crew and Demmas' forces bursts into the palace. Paris releases Tuvok, while Neelix places the synaptic stimulator on Kes/Tieran. Tieran jumps to a new host body — Ameron — but Kes places the device on him and Tieran is finally destroyed. Demmas, the rightful heir, becomes Autarch.