Star Trek: Season 2, Episode 13

Obsession (15 Dec. 1967)

TV Episode  -   -  Action | Adventure | Sci-Fi
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Capt. Kirk obsessively hunts for a mysterious cloud creature he encountered in his youth.



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Title: Obsession (15 Dec 1967)

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Episode complete credited cast:
Stephen Brooks ...
Jerry Ayres ...


Captain Kirk is haunted by a creature from his past when conducting a mining survey on a planet. He first encountered it as a lieutenant aboard the U.S.S. Farragut and blames himself for freezing in a moment of crisis, causing the death of many crewmen. The creature is a cloud-like, gaseous being that lives on the red blood cells found in humans. Obsessed by his desire for revenge and to erase the memory of 11 years ago, he pursues the creature relentlessly, putting in jeopardy an assignment to collect essential medical supplies. Written by garykmcd

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Release Date:

15 December 1967 (USA)  »

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Aspect Ratio:

1.33 : 1
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Did You Know?


"Obsession" is a "startrekified" version of Herman Melville's Moby Dick, a seminal American novel first published in 1851. Captain Kirk of the Enterprise is Captain Ahab of the Pequod and the Gaseous Creature is the White Whale. See more »


In the first scene, Spock phasers off a sample of rock, which has been clearly pre-cut to fall off on command. See more »


Dr. McCoy: Crazy way to travel, spreading a man's molecules all over the universe.
See more »


Featured in Bring Back... Star Trek (2009) See more »

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User Reviews

Military Drama Posing as a Space Monster Adventure
11 October 2007 | by (Vulcan) – See all my reviews

Obsession features a great Art Wallace script and solid performances by Shatner, Kelley and Nimoy. An away team is investigating a seemingly uninhabited planet, while carrying a cargo of medical supplies to a rendezvous for which they can't be late. A mysterious gas cloud attacks and kills a trio of red shirts by consuming their red corpuscles. Kirk recognizes the smell (literally) of all of this and explains that the last time he encountered this creature, half of his ship's crew was killed. The son if the captain Kirk served with is now a member of the Enterprise crew (Stephen Brooks) and Kirk believes that his hesitation doomed his crew mates. Soon, Kirk's obsessive behavior regarding the gas cloud has the crew questioning his sanity.

Ralph Senensky's direction keeps this classic Shatner episode tight, exciting, and well shot. There are many memorable scenes and the script allows for some very good character development for the young ensign as well as the principal cast members. And unlike the standard Star Trek Space Monster story, this ends up being as much a human-military (naval) drama as it is an adventure tale.

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