This is undeniably one of the best STAR TREK movies, up there with THE UNDISCOVERED COUNTRY and FIRST CONTACT. It begins with a training exercise that introduces the half Romulan/half Vulcan crew member Saavik (Kirstie Alley), who is a prodigy of Captain Spock's. Admiral Kirk is visiting, though he's a bit depressed because it's his birthday. McCoy visits him at his San Francisco home and gives him a pair of reading glasses since he's allergic to the typical treatment for near-sightedness. There's also the crew of the Reliant, which is looking for a lifeless planet to test the new Genesis experiment on. They land on the inhospitable world and are surprised to find cargo containers. Chekhov, the second in command, sees the word "Reliant" and immediately realizes who this all belongs to. When Khan and his people show up this is confirmed, much to his dismay. Khan blames Kirk and the Federation for stranding them on this planet all those years ago--and wants revenge. They take over the Reliant, which is overseeing an experiment involving a device called Genesis. In charge of this experiment is Dr Carol Marcus and her son David. She had a fling with Kirk long ago and David is his son.
When Kirk gets a cryptic message from Carol he and the Enterprise go to investigate--and encounter the wrath of the utterly insane Khan (Ricardo Montalban). What makes this movie so effective is that the stakes are so high. Lots of people die, including fan favorite Spock. This movie is as exciting as Star Trek: The Motion Picture was boring.