Star Trek: Season 2, Episode Thirteen “Obsession”

Stardate: 3619.2 (2268)
Original Air Date: December 15, 1967
Writer: Art Wallace
Director: Ralph Senensky

“It is malevolent, it’s evil… it must be destroyed.”

Rating: 4 out of 5.

The Enterprise is conducting a survey of Argus X, a planet which Spock notes is rich in pure tritanium, a mineral which is 21.4 times as hard as diamond. Suddenly, a smoke cloud spills over the rocks and Kirk smells the strange scent of honey in the air, it reminds him of a similar incident some 11 years ago. He asks his fellow crewmen to scan for the mineral dikironium. Then two red shirts are killed, with every red corpuscle removed from their bodies, and one is left in critical condition. Meanwhile the USS Yorktown is expecting an imminent rendezvous with the Enterprise for vital medical supplies. The Enterprise is carrying a collection of perishable vaccines which are badly needed on Theta VII, but Kirk refuses to deliver the vaccines right away, he has become fanatically obsessed with destroying this strange cloud-creature.

Ensign Rizzo (Jerry Ayres) is the red shirt who has survived the cloud attack, he is in critical condition in sickbay. Kirk visits him and asks Bones to bring Rizzo to consciousness for inquiry. Kirk then interrogates Rizzo about the creature –apparently, Rizzo recalls the smell of honey and he thinks it is intelligent. Ensign Rizzo dies shortly thereafter and he is replaced on the bridge by his friend Ensign Garrovick (Stephen Brooks), a name which Kirk curiously recognizes. Dr. McCoy and Spock read through old Federation tapes (thankfully Spock reads much faster than McCoy) and they discover that 11 years ago, the USS Farragut faced a strikingly similar monster. Half the crew was killed (some 200 people), including Captain Garrovick, father of the Enterprise’s newest Ensign. Interestingly enough, a young Kirk was aboard the Farragut at the time of the attack. Captain Garrovick had been Kirk’s commanding officer since his Academy days, and Kirk calls him one of the finest men he ever knew. Thus, vengeance on the cloud monster is deeply personal for him.

Kirk grows irritable when certain crewmen question his decision to hunt down the monster instead of delivering the vaccines. When the cloud creature vacates the planet, Kirk channels Captain Ahab as the Enterprise maddeningly pursues it through space. Spock notes that the cloud creature appears to exist in a borderline state between matter and energy, it can apparently change its own molecular make-up, and Spock also suggests that it may use gravity to propel itself. Scotty warns Kirk that the Enterprise could blow up at the speed it is traveling, but Kirk still demands the Enterprise upgrade to Warp 6. Suddenly, the creature halts in space and turns around to face the Enterprise. Kirk orders all levels to battle stations. The Enterprise fires phasers and photon torpedoes but to no avail. The creature then overtakes the Enterprise, entering through air vents, and it attacks two people. The creature remains in the vents (why?), leaving the crew with only 2 hours of breathable air.

Spock attempts to console Ensign Garrovick who blames himself for this whole situation –he hesitated firing his phaser at the creature back on Argus X (much like a young Kirk once did) but the creature suddenly begins emerging through the air vent and Spock remains in Garrovick’s room to prevent the creature from running amok throughout the ship. Spock is saved only because his hemoglobin is different from humans –the creature wants human blood rich in iron, not Vulcan blood which is composed of copper. Scotty then apparently floods the vents with radioactive waste (wouldn’t this affect the rest of the Enterprise’s breathable air?), but it drives the cloud creature back into space.  

Kirk believes the creature is headed for the Tycho star system, specifically the fourth planet, where the USS Farragut was attacked 11 years ago. Spock claims there is evidence the creature will spawn here (what evidence?), perhaps breaking apart and reproducing itself into thousands of replicas. Kirk and Ensign Garrovick beam down to Tycho IV to use an anti-matter device and destroy the creature, however setting off this device may also cause problems with the transporter. However, they employ hemoplasma as bait but it fails, so Ensign Garrovick and Kirk battle over who will lure the creature until Kirk decides to order Spock to beam them both back up while simply detonating the anti-matter device at the same time. Avoiding a close malfunction, both Kirk and Garrovick are beamed aboard in the nick of time. “Captain, thank heaven,” exclaims Scotty, to which Spock responds, “Mister Scott, there was no deity involved. It was my cross-circuiting to B that recovered them.” Dr. McCoy then whimsically interjects, “Well, then, thank pitchforks and pointed ears!”


The Shatner acting or “Shacting” is peak in this episode, a story which presents a unique glimpse into Kirk’s pre-Enterprise history. Up until now, much of his personal life has been somewhat mysterious. However, this episode is quite evidently intending to mirror Herman Melville’s Moby Dick though this has been rather more convincingly done elsewhere. Personally, I did not really care for the erratic and unlikable portrayal of Kirk in this episode, a caricature which seems all but sure to invite mutiny on the Enterprise. As a result, there are odd moments of recklessness in this episode –from Kirk’s megalomania, to Ensign Garrovick chucking a tray at his room’s ventilation switch. The Enterprise is not the regimented and collected military unit it was designed to be in this episode. Should Kirk be punished by Starfleet for holding up the transportation of vital vaccines? His personal vendetta aside, this would surely be a punishable offense –even if he did rescue the galaxy from the terror of thousands of cloud monsters.The notion that the cloud monster might be imminently reproducing struck me as partly contrived in order to create a sense of urgency at the end and to justify this mad mission.

Nevertheless, in keeping with the high quality of episodes in Season 2, “Obsession” is still a nice installment with a uniquely protean enemy alien. This is neither the first nor the last alien encountered by the Enterprise with powers beyond human comprehension.


Writer Art Wallace (?-1994) wrote scripts for a variety of television shows, particularly Dark Shadows. He also later co-wrote the Season 2 Star Trek “Assignment: Earth” with Gene Roddenberry.

Director Ralph Senensky (1923- Present) is apparently still alive as I write this review making him nearly 100 years old. He directed many episodes of classic television including an episode of The Twilight Zone and six episodes of Star Trek.

Star Trek Trivia:

  • A recurring red shirt named Leslie (Eddie Paskey) dies in this episode, however he continues to appear in future episodes until he departs mid-third season.
  • Spock says the hemoglobin in his Vulcan blood is based on copper not iron in this episode.
  • The smoke for the cloud monster was created using an offscreen smoke machine.
  • In addition to its blatant nods to Moby Dick, D.C. Fontana also once noted its similarity to ”The Doomsday Machine.”
  • During this episode’s production, Ralph Senensky left to celebrate Yom Kippur allowing John Meredyth Lucas to direct a portion. This became his first of several future directorial efforts on the show.

Click here to return to my survey of the Star Trek series.

3 thoughts on “Star Trek: Season 2, Episode Thirteen “Obsession”

  1. Not an episode that I care for much nowadays. But certainly a very good one for Shatner when it comes to showing Kirk at his most conflicted. Thanks for your review.

    Liked by 2 people

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