Star Trek III: The Search for Spock

Star Trek III: The Search for Spock is a 1984 science fiction film, and the third film based on the Star Trek series.

Plot
Following the battle with Khan and the death of Spock, the badly-damaged and barely operational USS Enterprise returns to Earth, where Admiral Kirk is informed that the ship will be taken out of service, and the crew will be going their separate ways. Shortly afterwards Kirk is confronted by Spock's father, Sarek, who demands to know why Kirk left Spock's body on the newly-formed Genesis Planet, and mistakenly believes that Spock transferred his mind into Kirk before his death. The two discover that Spock actually transferred his mind into Dr. McCoy's body and is influencing his actions, and when McCoy is arrested for trying to book transport to the Genesis Planet, Kirk and his command staff are forced to break McCoy out of prison and steal the Enterprise. Meanwhile, the science vessel USS Grissom takes Lt. Saavik and Kirk's son, Dr. David Marcus to the Genesis planet, where they beam down and are shocked to find a resurrected, but juvenile Spock. Before they can decide what to do, the Grissom is suddenly destroyed by a Klingon Bird-of-Prey under the command of Kruge, a Klingon warlord who wants to seize control of the Genesis Project, setting up a deadly confrontation between the Klingons and the Enterprise.

Why It Rocks

 * 1) The film deals with the consequences of the previous film in a realistic way, with the use of a device that can create entire planets naturally causing just a bit of controversy among the other galactic governments.
 * 2) The characters have to jump through several hoops in order to fully restore Spock, rather than just having Saavik and David finding him on the Genesis Planet instantly restored to normal.
 * 3) Kruge is understated, but an effective villain with some layers to his characterization. He executes a gunner who "accidentally" destroys the USS Grissom and then acts like murdering an entire crew of defenseless scientists is no big deal, instantly sees through Kirk's attempt to bluff him during the battle between their ships, and is left in visible grief when nearly his whole crew is wiped out.
 * 4) Introduces the definitive look for the Klingons, who had been previously shown as just hairy dark-skinned humans on the TV show, and had some light forehead make-up in Star Trek: The Motion Picture. We also get the first steps towards the warrior race they would develop into on Star Trek: The Next Generation and beyond, with Kruge executing a gunner for his dishonorable actions in "accidentally" destroying the defenseless Grissom, and seeing the climactic battle with Kirk as a win-win situation since he'll either capture the Klingons' greatest enemy, or die a glorious death fighting him.
 * 5) *The movie also introduces the Klingon Bird-of-Prey, which would continue to appear in one form or another until the end of mh:besttvshows:Star Trek: Enterprise, over twenty years later.
 * 6) Brings back Spock's father, Sarek, for the first time since his one-off appearance in the TV series (the second if you count his briefly appearing in Star Trek: The Animated Series), and Mark Lenard gives another good performance, especially when Spock's mind is being restored to his resurrected body.
 * 7) The sequence where Kirk and his crew steal the mothballed Enterprise from under the noses of both Starfleet and the much more advanced ship designed to replace it is awesome.
 * 8) While Uhura is once again sidelined, for the most part, she does get a memorable scene when she locks a cocky young transporter operator in a closet at gunpoint to help Kirk and crew beam aboard the deserted Enterprise.
 * 9) Sulu gets a great moment during the prison break when he beats up a far larger security guard who mocked his height.
 * 10) The lead-up to the battle between the Enterprise and Kruge's cloaked ship is very tense. The actual battle then has a surprisingly realistic result with the Enterprise, which had been severely beaten up in the previous film and not repaired, managing to only get one shot off before the Klingons return fire, completely frying the ship's already-damaged systems.
 * 11) David Marcus gets a shocking and tragic death scene, getting stabbed to death by a Klingon while defending Saavik and Spock. This then leads to a distraught Kirk angrily cursing out Kruge, letting William Shatner do some of the best actings of his career.
 * 12) The USS Enterprise, after appearing in two TV shows and three films, is finally destroyed after Kirk sets the ship to self-destruct and actually turns out not to be just trying to bluff the Klingons into surrender. The scene itself is kind of emotional, since people who watched the show have seemed to have connected it well and feels as much of a loss as if a character was killed. The effects used for the ship's actual destruction are also very well-done.
 * 13) Introduces a whole new set of Starfleet ship designs, such as the Excelsior Class. Previously, all Starfleet ships either just re-used the Enterprise model, or a heavily modified version of it (as with the USS Reliant in the previous film).
 * 14) The visual effects are very good, arguably the best in the original cast films outside of the much higher-budgeted Star Trek: The Motion Picture.
 * 15) Another great soundtrack by James Horner.
 * 16) Despite the film's ending having Kirk contemplating everything that's happened - he's lost his ship, his son, and almost certainly destroyed his career - it then ends on a hopeful note with the resurrected Spock recovering enough of his memories to recognize Kirk and the rest of the crew.

Bad Qualities

 * 1) The plot can get a bit predictable at times.
 * 2) It's never actually explained why Kirk needs to bring Spock's body and mind back to the planet Vulcan, considering that neither he nor Sarek knew Spock had been resurrected until late on in the film. A deleted scene explained that Sarek actually wanted to perform an ancient Vulcan ritual that would have preserved Spock's mind for all eternity, but it was likely cut because this would have just introduced another plot hole (why they needed Spock's body for that instead of just taking his mind directly out of Dr. McCoy).
 * 3) Saavik's new actress, Robin Curtis, is kinda bland and not nearly as memorable as Kirstie Alley was in the previous film.
 * 4) The sets for the Genesis Planet look really fake at times, and barely any better than what you'd have seen on a planet of the week in the series.
 * 5) While David's death is a tragic moment, it's not really relevant to the story outside of being a case of the "he tampered in God's domain and so must die" trope, and robs us of more character development we could have gotten for Kirk (though Star Trek VI: The Undiscovered Country would later manage to make something out of it).
 * 6) The plot-twist of Spock still being alive makes his death in "The Wrath of Khan" pointless.

Reception
The film received positive reviews from critics, audience, and fans of the series, while review aggregator Rotten Tomatoes has given it 80%, indicating positive reviews.