Kirk (William Shatner) and his crew are returning to Earth to face disciplinary action for their rescue of Spock (Nimoy) in the last movie. Meanwhile, there’s an alien probe headed toward Earth that’s destroying everything in it’s path. The crew deducts that the probe’s signal is based from the sounds of a humpback whale. They need a humpback whale to respond to the signal, but since they are extinct in the 23rd century, they have to time travel to San Francisco in the 1980’s to get some whales!
To avoid freaking out the natives, Spock covers up his ears with a headband. While there, Kirk almost gets hit by a car and calls the driver a “Double Dumbass”. Spock and Kirk hop on a bus and Spock gives an unruly punk the Vulcan neck pinch, and in the film’s best scene, Kirk teaches Spock how to swear. Catherine (Child’s Play) Hicks plays a friendly oceanographer named Gillian (a role originally intended for Eddie Murphy!!!) who gives them a tour of an aquarium which houses two whales named George and Gracie and Spock hops in the tank and mind melds with them. Gillian learns that the whales are going to be returned to the wild, so she agrees to help them save the whales. Scotty (James Doohan) and McCoy (DeForest Kelley) go and help a manufacturer invent “transparent aluminum” to make a tank for the whales. “If we give him the formula, we’ll be altering the future!”
“How do we know he didn’t invent the thing!”
Meanwhile, Uhura (Nichelle Nichols) and Chekhov (Walter Koenig) are trying to steal plutonium for the ship’s drained Dylithium Crystals. Chekhov gets captured and is injured and taken to a hospital. Back at the aquarium, the whales are let loose into the Alaskan waters and Gillian and Kirk go and rescue Chekhov. Once they are all onboard the ship, they discover the whales being hunted, and they save them in the nick of time. They head back to the 23rd century and crash land in San Francisco Bay. The whales signal the probe and the crew yet again saves Earth from destruction. Kirk gets brought up on charges for rescuing Spock against orders and for blowing up the Enterprise. Since he saved the planet, they slap him on the wrist and reduce his rank to Captain. In the end, he gets to take the newly renovated Enterprise for a test spin.
Nimoy shows a flair for comic timing, both behind and in front of the camera, and the supporting cast is given more to do than usual. It’s a lot of fun and is probably the most accessible film for non-Trekkies (It was also the highest grossing of the series.), although the lightweight material leaves no room for Shatner’s over the top theatrics. Also starring Mark Leonard, John Schuck, Michael Berryman, Jane Wiedlin, and Brock Peters. Nimoy also directed Three Men and a Baby.