Return of the Living Dead 3 is the second installment after Return of the Living Dead (1985) but bears little resemblance to its predecessors. It drops the comedy that had defined the series prior and replaces it with a serious romantic theme. It is followed by Return of the Living Dead: Necropolis (2005).
When Curt Reynolds (J. Trevor Edmond) steals his father's security key card, he and his girlfriend, Julie Walker (Melinda Clarke), decide to explore the military base where his father works. Using the card, they sneak into a hangar and observe Curt's father, Col. John Reynolds (Kent McCord), Col. Peck (James T. Callahan) and Lt. Col. Sinclair (Sarah Douglas) overseeing an experiment with a corpse.
The corpse is exposed to 2-4-5 Trioxin gas. Trioxin, developed in the late 1960s, re-animates the corpse into a zombie. The military's intention is to use zombies in warfare as expendable soldiers. However, once re-animated, the zombies are difficult to control.
To solve this problem, Sinclair would like to attach the zombies to exoskeletons, which could be locked down when the zombies were not in battle. Reynolds takes a different approach: his scientists developed a method of "paretic infusion" to paralyze the zombie until it is needed. They fire a chemical bullet into the forehead of the zombie which creates a localized endothermic reaction that freezes the creature's brain. At first, the paretic infusion test looks successful, but the effect wears off much quicker than they expect and the reanimated zombie comes back to life and bites Dr. Hickox's fingers off. The zombie then proceeds to bash Hickox against a wall until he is dead. Having been infected by the zombie, Hickox is re-animated as another zombie and starts biting one of the other technician's legs while the technician begs and pleads for mercy. Hickox is paralyzed with bullets and everyone in the room is quarantined. The magnitude of this failure causes Reynolds to be re-assigned to Oklahoma City and Sinclair to be promoted to head of the project.
When Reynolds informs Curt that they'll be moving again -- something they've done a dozen times in Curt's life already -- Curt refuses. Angrily, he storms out of home riding off on his motorcycle with Julie. While the bike speeds down the road, Julie playfully grabs Curt's crotch, intending to play with his genitalia. This causes Curt to lose control of the motorcycle, then he veers into the path of an oncoming truck, swerves and slams strongly into the road guard rail. Julie flies off the bike, slams violently against a telephone pole and dies instantly by neck breaking.
Distraught, Curt brings Julie's corpse back to the military base. Using the key card again, he sneaks her in and uses the Trioxin gas to re-animate her. Julie initially seems perfectly normal (most likely due to her extreme "freshness" as a corpse, having only been dead for less than an hour), but soon starts exhibiting symptoms, such as pain (from rigor mortis and the general state of being dead, as mentioned in previous movies) and hunger pains that cannot be satiated by regular food. An attempt to do so in a convenience store accidentally leads to a confrontation with a Hispanic street gang, where the Chinese owner is shot and left for dead - and turns into a zombie as well. Julie bites and infects Mogo, one of the gang members. This leads to a subplot of the gang chasing Julie and Curt through the city, not realizing what is happening to their infected friend. Trying to hide from the gang in the sewers, they encounter a vagrant that calls himself Riverman, who takes them in and hides them. He gives Curt a coin, saying it is a representation of his philosophy of "if you meet someone, do them some good, then tell them to pass it on". In the meantime, the military has learned of Curt's break-in and Julie's exposure to the Trioxin. While Curt's father is extremely worried about his son's welfare, Lt. Col Sinclair couldn't care less. She is only interested in reclaiming a valuable test subject.
Back in the underground, Julie discovers that extreme pain seems to make the cravings to feed on humans go away for a while, which leads to a scene where she adorns herself in "S&M zombie" gear scavenged from the debris around Riverman's lair, complete with a large shard of glass driven through one hand, and a piece of leather, weighted down with a rock, pierced through the other. This actually comes in handy when the gang finally tracks Julie and Curt down. In a very messy confrontation with the gang, she uses her new decorations to stab, beat, and otherwise kill several of the members. Unfortunately, her body starts to become numb to the pain over time, and she winds up turning on Riverman, infecting and killing him. Things seem very bleak for the survivors until they are "rescued" by the military.
With the remaining gang members shot, Curt is arrested and taken back to the base, and Julie is impounded as military property by Sinclair. Curt manages to escape and rescue Julie, but in the process he winds up setting off a chain of events that free the remaining original Trioxin zombies from their containers. While trying to escape, Curt and Julie encounter none other than Riverman, who is now locked into one of Sinclairs's prototype exoskeletons. Sinclair soon finds out the exoskeletons aren't quite as effective as a means of restraint as she had hoped (which incidentally leads to her death). Riverman is about to kill Curt as well, until Curt displays the coin Riverman gave him earlier. This apparently brings to the surface enough humanity to cause Riverman to spare Curt and Julie.
By now the entire facility is on a countdown to incineration. Most zombies inside the base were shot down and destroyed. Curt and Julie are nearing the exit, when the last Trioxin zombie manages to bite and infect Curt before dying forever. Realizing that he is now infected and then will become a zombie in a few moments, Curt decides at the last moment not to escape, despite his father's pleading. His father watches in horror as Curt and Julie deliberately climb inside the crematorium. The two lovers then share a final embrace as the flames surround them and the screen fades out.
- Kent McCord as Col. John Reynolds
- James T. Callahan as Col. Peck
- Sarah Douglas as Lt. Col. Sinclair
- Melinda Clarke as Julie Walker
- Abigail Lenz as Mindy
- J. Trevor Edmond as Curt Reynolds
- Jill Andre as Dr. Beers
- Michael Decker as Science Technician
- Billy Kane as Waters
- Mike Moroff as Santos
- Fabio Urena as Mogo
- Pia Reyes as Alicia
- Sal Lopez as Felipe
- Dana Lee as Captain Ping
- Ray Downie as Cop #1
- Michael Northern as Squad Soldier
- Basil Wallace as Riverman
- Joe Sikorra as Squad leader
- David Wells as Laboratory Technician
- Cadaver Hughes as Cadaver
- Anthony Hickox as Dr. Hickox
- Brian Peck as Ballistics Technician
- Jimmy Marshall as Cop #2
- Otto Scottway as Drunk Zombie
- Ronnie Pellicci as Pie Eating Zombie
- David Boyce as Zombie Slug Boyce
- Cecil Garrett Esq 3rd as Zombie Cecil