Kirk, Spock and some red-shirts are on a planet searching for unobtanium. Suddenly Kirk starts smelling gas. Apparently, he recognizes a sickly-sweet smell from eleven years earlier when he was on the USS Farragut and it was attacked by a hemoglobin drinking gas cloud. During this present mission the cloud kills off all the red-shirts.
This smelly gas cloud is Kirk’s white whale. He is feeling guilt over having hesitated firing a phaser that might have saved his Captain’s life back eleven years ago. By coincidence, the son of the late captain, Ensign Garrovick, is in the Enterprise’s crew and Kirk takes this young man down to the planet’s surface for another chance to kill the cloud. Garrovick hesitates for two seconds when surprised by the cloud and more red-shirts are killed. Kirk blames Ensign Garrovick for the death of the men. Now the creature flees the planet and the Enterprise pursues at Warp 8. Eventually the creature turns to fight. Phasers and photon torpedoes do nothing and the creature manages to enter the Enterprise where it kills a few more men. The creature attacks Spock but his copper-based globin is inedible. Suddenly the creature leaves and heads off at Warp speed. Kirk figures it’s going back to where it attacked the Farragut and that it’s going to spawn a multitude of offspring. Spock tells Kirk to use an “ounce of anti-matter” to destroy the creature. Kirk and Garrovick become bait for the creature and at the last second, they are transported away and the anti-matter is unleashed. The blast interferes with the transporter and Spock and Scotty barely get the two men to rematerialize.
This episode features Kirk obsessed with destroying the creature that killed the captain that he admired coming out of the Academy. Bones and Spock get to question Kirk’s judgement but eventually understand the danger of this creature. There is a scene where Ensign Garrovick and Kirk fight over who would stay last while the creature is lured to the anti-matter. Several times in the episode Kirk loses his temper. This is a so-so episode. Let’s call it a 5 // 4.