Star Trek: Obsession

"Obsession" is a second season episode of the American science fiction television series, Star Trek and was broadcast on December 15, 1967. It is episode No. 42, production No. 47, written by Art Wallace, and directed by Ralph Senensky. In the episode, Captain James T. Kirk becomes obsessed with destroying a deadly entity he once encountered in his youth. The episode deals with several human emotions: guilt, fear, obsession and, ultimately, redemption. While Captain Kirk is the primary focus, the viewer sees glimpses of these emotions in other members of the ship. At various times the "fight or flight" instinct is shown as an internal battle which one has to overcome in order to find emotional peace.