Having saved their comrade Captain Spock, the crew of the late starship Enterprise decide to return home to face court martial for their actions. However, an alien probe of tremendous power arrives in Earth orbit and drains the planet of energy, whilst sending out incomprehensible transmissions. Analysing the transmissions, Admiral Kirk and his crew determine that the probe is attempting to communicate with humpback whales, a species rendered extinct due to the actions of humans three hundred years earlier. With little choice, the crew decide to time travel to the late 20th Century to try to recover two whales to help them save humanity.
As a seven-year-old back in 1986, I remember reading reports about the new Star Trek movie in production. The story - that the crew would go back in time to save the humpback whale from extinction with a right-on environmental message, the Enterprise would not appear and the film would have a comedic tone - sounded second only to Spock's Brain in cringe-inducing awfulness, and I braced myself for a terrible movie.
Which just goes to show. Star Trek IV: The Voyage Home is, easily, the most breezily enjoyable popcorn flick in the entire Star Trek canon. In terms of raw dramatic power and thematic richness it can't hold a candle to The Wrath of Khan, but it doesn't even try. Instead it leans heavily on the warmth and comedic interplay of the crew, celebrating twenty years of working together in this film. Everyone is on top form, Leonard Nimoy delivers arguably his best work as both director and actor, William Shatner gets to deploy his formidably-weaponised wit and charm (somewhat missing from the three previous, more sombre films) and the other actors all get their time in the sun.
The film does feel a bit over-familiar in some aspects: the opening with an alien object of tremendous power approaching Earth is pretty much a replica of Star Trek: The Motion Picture (fortunately this probe only knocks ships out rather than scanning them to death), and the ships in the film are all suspiciously the same as the four extant Starfleet ship models (the Constitution, Miranda, Excelsior and Oberth classes, by this point). But this is all (well-handled) setup to the central gag of getting our characters to 20th Century Earth and seeing them try to cope in a "paranoid, primitive culture." The culture clash gags are amusing - even moreso now that we are so far removed from 1986 San Francisco that it appears to be a historical time period itself - with the crew struggling with concepts like money and public transport. Once the crew find their feet, the film becomes even more entertaining, with Dr. McCoy giving a dialysis patient a tablet that instantly regrows her kidney, Scotty and McCoy creating a self-repeating temporal paradox by giving the inventor of transparent aluminum the formula, Chekov getting into hot water for asking about "nuclear wessels" and Spock mind-melding with a whale. Rarely does a scene pass without a genuinely great, comedic line ("You are not seeing us at our best," "That much is certain").
There are some spotty plotting moments, including why they went back to 1986 to recover whales when their numbers were already depleted rather than, say, the middle of the 6th Century BC and just beaming them up, though I like the idea of Spock deciding to communicate with them and bring them on-board with the plan; they are sentient beings, after all (that said, one line suggests that Spock recreated the timejump parameters by memory from their last jump in the original TV series, in which they travelled back exactly 300 years, so that may have been the limitation here). The Klingon Bird-of-Prey also continues its somewhat elastic connection with any kind of scaled reality, dramatically shifting in size depending on the needs of the scene. But this isn't a film about nitpicking or pedantry. It's a feel-good adventure, especially after the heavy drama of the previous two flicks, and it works extremely well on that basis.
Particularly strong is the script, which is packed with delights. The original script wasn't working so producer Harve Bennett convinced Wrath of Khan co-writer and director Nicholas Meyer to return for a script polish-up, adding a lot of character and warmth to proceedings. The script also intelligently addresses the outstanding plot issues from the previous two films, with Kirk and his crew having to face the consequences of their actions. The claim that Star Trek II, III and IV form a trilogy is overstated - the three films merely acknowledge the previous films happened and there is some plot business from them that needs to be dealt with - but it's good to see continuity being handled well and logically.
The film also works well without a villain: The Motion Picture tried that but it didn't entirely work. Here it's handled much better. The superbly-realised and somewhat eerie probe is the closest thing we have to an antagonist and it's more of a force of nature than a character, though some may feel disappointed we don't learn more about its origins (the entertaining novel Probe does provide some interesting ideas about its origins, non-canon though it is). John Schuck - who later appears as Draal in Babylon 5 - makes a good but brief impression as the belligerent Klingon Ambassador to the Federation who is out for Kirk's blood, and he reprises that role in Star Trek VI: The Undiscovered Country (which can be seen as something of a stand-alone "sequel" to the "Genesis Trilogy," as limited as those connections are).
The film is also notable for its distillation of the Star Trek ethos: the probe is a potential threat, but not mindlessly belligerent. Violent solutions to the situation are rejected in favour of peaceful ones. The hunting of intelligent beings to death just for their meat is deemed by Spock to not be "logical." The short-sightedness of humanity against its long-term interests is repeatedly mentioned. Arguably the film's most interesting moment is also its most subtle: in his mind-meld, Spock asks the whale Gracie to help save humanity from the probe and she agrees, despite learning her species is destroyed just a few decades later by the actions of humanity, a subtle suggestion that the morality of whales is superior to that of humans.
Star Trek IV: The Voyage Home (****½) is unalloyed fun from start to finish, hampered maybe by a few clunky lines of dialogue and one or two gags that don't land as well as most. Maybe not quite the best Star Trek film, but certainly the most watchable and the most fun, augmented by Leonard Rosenman's distinctive and unusual-for-Star Trek score and some great visual effects (the film's animatronic whale models are particularly impressive). One of the main legacies from the film was Leonard Nimoy and William Shatner's high salary demands, which made the viability of future films doubtful and spurred Paramount to commission a brand new television show with a new, cheaper cast. Star Trek: The Next Generation was announced just before the film launched, but the "classic" cast would still have two more appearances to come.