This is of course a sequel to Space Seed from the original Star Trek series. In that episode, Kirk and the Enterprise gang find a derelict ship with superhuman survivors in hibernation. These survivors are revived and they take over the Enterprise for a bit, but the intrepid Kirk gets the upper hand and places them on a primitive planet. Richardo Montalban is the head superhuman, Khan. In this movie, Chekhov is on an expedition and, to make a long story short, lands on the same planet to which Khan and the group were banished. Khan of course takes over that ship and then uses it almost to destroy Kirk and the Enterprise. The wily Kirk outfoxes Khan due to Kirk's experience. Kirk also meets his natural son and that is a whole new story. 