The overthrow of the Autarch of Ilari by Tieran, a long-dead tyrant who survived by moving his mind from body to body and who took control of Kes to seize power.
In the Voyager episode Warlord, the crew rescue three Ilari from a damaged ship. One of them dies, and the mind he carried, that of the former ruler Tieran, passes into Kes. Using her body and her growing mental powers, Tieran steals a shuttle, kills the reigning Autarch and proclaims himself ruler once more.
The Autarch's elder son Demmas escapes and asks Voyager for help, while Tieran tries to win over the younger son, Ameron. Tuvok is captured during an attempt to reach Kes but manages a mind-meld that lets her begin fighting back from within.
A joint assault by Demmas's supporters and Voyager's crew ends the coup. Tieran flees into another host, and a synaptic device finally destroys him. Demmas takes his father's place, and Kes is left shaken by what was done through her.