Star Trek #4: The Peril of Planet Quick Change

Stardate 21:06.7

A planet is continually changing its dynamic makeup. Spock is also taken over by some of the very spirits of the aliens. The whole Enterprise Crew works hard to stabilize the planet led by Spock under control of the aliens. This is kept from everyone and Spock finds later that he is unable to act independently from the alien control. When everything is done Spock finds one soul does not want to leave and he tries to break free from his possession.