-> '''Laurie Strode''': You've heard the story?\\
'''Will Brennan''': Who hasn't? Michael Myers. It's like 20 years ago?\\
'''Laurie''': 1978.\\
'''Will''': And the girl that...what happened to the sister, she died, right?\\
'''Laurie''': No, she faked her death... and now, she's the headmistress of a very posh, secluded private school in Northern California -- hoping and praying every year...that her brother won't find her.

Ignoring the continuity of the [[Film/Halloween4TheReturnOfMichaelMyers last]] [[Film/Halloween5TheRevengeOfMichaelMyers three]] [[Film/HalloweenTheCurseOfMichaelMyers films]] of the ''Franchise/{{Halloween}}'' franchise, ''Halloween [=H20=]: Twenty Years Later'' picks up the story of FinalGirl Laurie Strode (Creator/JamieLeeCurtis). After faking her death to live in peace following the horrific events during the [[Film/{{Halloween 1978}} Halloween night of 1978]], Laurie had changed her name to Keri Tate, had a son, and became a headmistress for a high school far away from Haddonfield, Illinois.

Michael Myers, however, has finally tracked Laurie down, and after two decades of waiting, he comes back into her life -- and enters the lives of a number of students, including Laurie's son -- in order to kill her once and for all...

While it offered a solid conclusion to the story of Laurie Strode, that didn't stop the suits from [[Film/HalloweenResurrection making a sequel]].
!! ''Halloween [=H20=]: Twenty Years Later'' contains examples of the following tropes:

* ActionGirl: Laurie has had enough of Michael's bullshit.
* AdvertisedExtra: Creator/JosephGordonLevitt, [[spoiler:whose character died in the opening scene]].
* AndStarring: There is "introducing Josh Hartnett". He has done quite well for himself ever since.
* ArcNumber: This film reveals the number seventeen to be this to the series. Michael murdered Judith and tried to kill Laurie when they were both seventeen, and John is now seventeen.
* ArtisticLicenseGeography: Michael drives from Haddonfield, Illinois to Northern California within 1-2 days. Even if he'd driven nonstop--which he didn't, he had to stop because his car broke down and steal another--that's impossible.
* BackForTheDead: Marion Chambers, who featured as a minor character in the first movie and played a bigger role in the second, returns in the prologue. Michael breaks into her house looking for details on Laurie. Naturally she doesn't survive the encounter.
* BallsOfSteel: Michael takes a knee to the groin, but barely reacts.
* BigEater: Sarah. While preparing a massive amount of junk food for a Halloween party, she mentions she's got such an intense love of food that it's actually a goal of hers to get fat. [[BigBeautifulWoman Charlie agrees with her philosophy]].
* BlackDudeDiesFirst: [[spoiler: Inverted. Ronnie the security guard is mistakenly shot by Will, but appears at the end having survived]].
* BloodyHandprint: Laurie leaves a bloody handprint on the door of a closet, tricking Michael Myers into thinking she was hiding inside.
* BrickJoke: A minor gag early in the film is Ronnie reading cheesy romance stories he's written to his wife over the phone. [[spoiler: In the climax, when he's survived, he can be seen on the phone to her excitedly saying he's going to write a thriller]].
* BuxomIsBetter: Ronnie is narrating a story to his wife, and we hear him talking about a woman with "round, melon breasts".
* CallBack:
** Michael [[spoiler: lifting Will up with his knife after stabbing him]] is reminiscent of the infamous scalpel scene from ''Film/HalloweenII1981''.
** Molly spotting Michael lurking across the street from her classroom, precisely as Laurie did in the first film--and both during an English class, no less.
** The numerous StealthHiBye Michael pulls are also straight out of the first film.
** The song "Mister Sandman" is played over the film's opening, like it was over the beginning and end of the second film.
** Laurie tells [[spoiler: John and Molly]] to go down to the street to get help from someone, just as she did for Tommy and Lindsey in the first film.
* CampingACrapper: Averted. A woman and her daughter go to a public bathroom and Michael Myers follows them in. After a tense scene in which the audience assumes he is going to kill them, he ends up stealing the woman's car keys instead.
* CanonDiscontinuity: Played with. The Jamie Lloyd portions of the franchise aren't mentioned (though they would have been in the original treatment) but it's hinted that they did happen - the photo montage at the start shows a bloody pair of scissors, as a nod to the fourth film.
* CarFu: Laurie hijacks an ambulance van with Michael in it, and runs it off a cliff in order to kill Michael once and for all.
* CaughtInASnare: Laurie has a snare trap set for Michael.
* CelebrityParadox: One of the college students watches ''Film/{{Scream 2}}''. Even though the first ''Film/{{Scream|1996}}'' showed ''Film/{{Halloween|1978}}'' being played.
* CharacterDevelopment: Laurie Strode, who goes from a DamselInDistress to a badass ActionGirl in this movie! She even provides the page image!
* CutPhonelines: At Laurie's school when Michael finds her.
* DangerousKeyFumble: Molly does this as Michael closes in.
* DepartmentOfRedundancyDepartment: The subtitle, considering on how ''[=H20=]'' already means that it has been twenty years from the first film's events.
* DisappearedDad: John's estranged dad is an "abusive chain smoking methadone addict."
* EvilOverlooker: The poster had Michael Myers' BlackEyesOfEvil looming over the frightened-looking protagonists.
* {{Foreshadowing}}:
** Laurie is teaching an English literature class on Mary Shelley's novel ''Literature/{{Frankenstein}}''. Molly, one of the students, responds to a question about the book and fate with this:
-->"I think that Victor should have confronted the monster sooner. He's completely responsible for Elizabeth's death. He was so paralyzed by fear that he never did anything. It took death for the guy to get a clue."'' She goes on to say that Victor finally confronts the monster because he ''"had reached a point in his life where he had nothing left to lose. I mean, the monster saw to that by killing off everybody that he loved. It was about redemption. It was his fate."
** This foreshadows the final scenes in the movie where [[spoiler:Laurie finally decides to stop running from Michael Myers and confront her monster. After twenty years of living in fear and seeing her loved ones murdered, she had nothing more to lose. It was time to face her fears and end the nightmare]].
* GroinAttack: Laurie knees Michael in the groin. [[BallsOfSteel It doesn't do anything except cause him to give her a nasty glare]].
* TheHunterBecomesTheHunted: At the end Laurie turns the tables on Michael Myers and starts hunting him down with an axe.
* InfantImmortality: [[spoiler: We're given a BaitAndSwitch thinking Michael will murder a mother and her young daughter, but he just steals their car keys. No victims are younger than a teenager]].
* {{Irony}}: Laurie initially refuses to let John go on the Yosemite camping trip but relents and gives him a permission slip at the last minute. He decides to stay at the school for a party - and gets attacked by Michael Myers.
* MamaBear: In the original movie, Laurie had no qualms attacking Michael in self defense. In ''H20'', she really lets him have it when he attacks her son.
* NonchalantDodge: Michael's response to Laurie's knife throwing act.
* OffWithHisHead: [[spoiler:Laurie beheads Michael in the end. The next film [[DeathIsCheap changed this greatly]].]]
* OddballInTheSeries: Alternate continuity or not, this is the first--and only--film in the series to not take place in Haddonfield (the prologue notwithstanding). It also takes place over several days, whereas the other films took place over one.
* OddlyNamedSequel2ElectricBoogaloo: No, the movie is not named after the chemical formula for water (H20 = Halloween 20 Years Later). Although, water has a PH of 7.0. And this is the seventh movie in the ''Halloween'' franchise.
* ProlongedPrologue: The prologue goes for almost 20 minutes before the opening credits begin.
* {{Recut}}: There's a TV Cut that trims the violence and cuss words, but also has some alternate scenes. One added scene gives the counselor played by Adam Arkin some development by revealing that his mother cheated on his traveling salesman father, and he got blamed for knowing, but doing nothing.
* SassyBlackWoman: Ronnie's wife. She manages to be this trope, despite never appearing on screen; only featuring on the phone.
* SayMyName: Laurie after she starts hunting Michael:
* SeriesContinuityError: Michael has no burn scars, which he would have incurred from the second film (which is on this movie's continuity).
* ShoutOut:
** One character is named Norma Watson after P.J. Soles' role in the first film adaptation of ''Film/{{Carrie|1976}}''. Soles also played Lynda in the original ''Halloween''.
** There is also a cameo by Creator/JanetLeigh, mother of Jamie Lee Curtis and star of ''Film/{{Psycho}}'', which is the Spiritual Ancestor to the original ''Halloween''. Janet Leigh drives the car she drove in ''Psycho'', and her scene is scored with the music from that film.
** One of the teens who Nurse Loomis encounters is wearing [[Franchise/FridayThe13th a hockey mask]].
** Laurie says "drive down to the Beckers", referencing Casey Becker from ''{{Film/Scream 1996}}'' - whose parents referenced Laurie's line from ''Halloween'' "drive down to the [=McKenzies=]."
* SlashersPreferBlondes: [[spoiler: Inverted. The lone blonde in the group is one of the few survivors]].
* StalkerShrine: It is revealed that Dr. Loomis' office is a shrine to Michael Myers, with three decades worth of newspaper clippings about Myers taped all over the office walls. To add to the creepiness, he also has high school photos of Laurie (Michael's sister) stuck to the wall too.
* SuddenSequelDeathSyndrome: [[spoiler:Marion Whittington and Doctor Loomis. Actor Creator/DonaldPleasence [[TheCharacterDiedWithHim passed away]] in 1995. At least his death was [[KilledOffScreen off-screen]] unlike Marion unfortunately.]]
* ThrowingYourSwordAlwaysWorks: Averted. During the final confrontation with Michael Myers, Laurie throws several large kitchen knives at him. They all miss.
* TookALevelInBadass: Laurie has had enough of being stalked by Michael and takes the fight to him.