Cathexis

Janeway's Gothic holonovel is interrupted when a shuttle returns from a dark matter nebula with Chakotay brain dead and Tuvok unconscious. Before long, crew members start changing Voyager's course and disabling systems, with no memory of their actions. The Doctor finds a common pattern in their brain activity: something is taking possession of people, one after another. The truth turns out to involve two intruders. Tuvok has been taken over by one of the Komar, noncorporeal beings who want to lure Voyager into the nebula so they can feed on the crew's neural energy. The other presence is Chakotay's own consciousness, moving between bodies to fight back, which is why the warp core was ejected to stop the ship. Once the possessed Tuvok is overcome with a magneton pulse, Chakotay uses his medicine wheel to guide the crew to safety. The warp core is recovered and the Doctor restores Chakotay.