After the events of the previous film, Michael Myers, Jamie Lloyd, and the Man in Black have vanished for six years and are thought to be killed in the explosion. The Man in Black is the leader of a druid cult by the name of Thorn. The Thorn cult has impregnated Jamie, who gives birth to a baby boy. The Man in Black takes the baby and paints the Mark of Thorn on him in blood, but later a nurse named Mary helps Jamie and the baby escape, though she is killed by Michael. Jamie gets in a truck (whose driver is killed by Michael) but he chases after her. She goes to the bus station and calls the radio for help, then goes to a barn where Michael impales her on a corn thresher and turns it on, killing her. However, he does not find the baby, since she hid him in the bus station.
Relatives of Laurie Strode have moved into the Myers house: Kara Strode, her son Danny (who has been hearing a strange voice), her younger brother Tim, her mother Debra, and her abusive father John. Tommy Doyle lives across the street from them, in a boarding house run by the mysterious Mrs. Blankenship. He is obsessed with finding out Michael's motives. He hears Jamie call for help on the radio, and goes to the bus station where he finds the baby, whom he names Stephen.
Dr. Loomis is retired, but Dr. Wynn wants him to return to Smith's Grove. Tommy tells Loomis that Michael has returned, so he goes to the Myers house and tells Debra to move her family somewhere safe. Debra calls John at Strode Real Estate, but he refuses to listen to her. Debra is then stalked and killed by Michael. Kara and Danny go to Tommy's house, and Tommy tells them that Michael has been marked with the mark of Thorn. The tribes of druids place the Curse of Thorn on one child from their tribe, who must then kill every member of his family as a sacrifice to keep the tribe alive. If Michael succeeds, the Curse of Thorn will be passed to someone else. This is why Danny has been hearing a voice, as Michael did when he killed his sister.
On Halloween night, John returns to his house, drunk, but everyone is gone, and Michael kills him. He then kills Barry Simms, Tim, and his girlfriend Beth. Kara and Danny return to Tommy's house where they, Tommy, and Dr. Loomis discover Stephen missing. Loomis realizes who the only other one who knew Tommy had the baby with him was. The Man in Black calls Danny upstairs, and is revealed to be Dr. Wynn. Mrs. Blankenship is revealed to be in the Thorn cult, and Kara jumps out the window to evade the cult members. Tommy and Loomis are drugged. They wake up to find Kara and the cult members gone. Loomis knows Wynn wants the final battle to be fought at Smith's Grove.
Kara has been locked in a cell by Wynn. Tommy and Loomis go to Smith's Grove and Tommy breaks Kara out of her cell before Michael can kill them. Tommy and Kara find Danny and Stephen just as Wynn and the other cult members enter the operating room. Michael grabs a machete, enters the room, and kills all the cult members except one doctor, who is later killed when Michael smashes his face against the bars.
Kara and Tommy face off against Michael in a room where Tommy injects him with corrosive chemical and beats him violently on the head with a metal pole, so that the chemical is gushing from the eyeholes of his mask.
Kara, Tommy, Danny, and Stephen leave Smith's Grove, but Dr. Loomis goes back to attend to an unfinished business. We see Michael's mask lying on the floor (next to the needle that was in the back of his neck), and hear Loomis's scream followed by the scrape of a knife, leaving the fate of both Loomis and Michael (even whether or not either lived or died) unknown.
No official sequel to this film has been made, in film or in comic. Instead, Halloween H20: Twenty Years Later was created as a direct and alternate sequel to Halloween II. Every Halloween comic in existence adheres to the H20 timeline. No "versus" films for Michael (like Freddy vs. Jason, and Alien vs. Predator) are planned, even though New Line participated in talks with John Carpenter about including him in a sequel to Freddy vs. Jason. The closest there is to a sequel to Halloween: The Curse of Michael Myers is a fan video depicting his death at age 60, and featuring a professional voice actor who voiced Dr. Loomis in H20.
It has sometimes been suggested that H20 takes place in the same timeline as the 4-6 timeline, but Resurrection does not. This may be because Resurrection was one of the least popular films in the franchise.
|#||Name||Cause of death||Killer||On screen death||Notes|
|1.||Mary||Head smashed against a spike||Michael Myers||Yes|
|2.||Truck owner||Neck broken||Michael Myers||Yes|
|3.||Jamie Lloyd||Impaled on a corn thresher||Michael Myers||Yes||First "sacrifice" by Michael since he killed his sister|
|4.||Debra Strode||Hit with an axe||Michael Myers||Yes|
|5.||John Strode||Electrocuted against console||Michael Myers||Yes||His head exploded|
|6.||Barry Simms||Stabbed||Michael Myers||Yes|
|7.||Tim Strode||Throat slit||Michael Myers||Yes|
|8.||Beth||Stabbed multiple times||Michael Myers||Yes|
|9.||Smith's Grove patient||Stabbed in stomach||Michael Myers||Yes||The stabbing was offscreen|
|10.||One nurse and eight doctors in the Thorn cult||Killed with machete||Michael Myers||Yes|
|11.||Dr. Bonham||Killed with machete||Michael Myers||Yes|
|12||Dawn Thompson||Killed with machete||Michael Myers||No||It is unknown whether she was there|
|13||Mrs. Blankenship||Killed with machete||Michael Myers||No||It is unknown whether she was there|
|14.||Dr. Terence Wynn||Killed with machete||Michael Myers||No||Fans speculate he may have survived|
|15.||Doctor in Thorn cult||Face smashed against bars||Michael Myers||Yes|
Whether or not Michael was killed when Tommy smashed his head in with a metal pole, or whether Michael killed Dr. Loomis offscreen, remains a mystery.