[[quoteright:300:http://static.tvtropes.org/pmwiki/pub/images/ikwydls.jpg]]
[[caption-width-right:300:Some people ''really'' don't know how to let things go...]]

->''If you're going to bury the truth, make sure it stays buried.''
-->-- '''{{Tagline}}'''

''I Know What You Did Last Summer'' (1997) is a horror/slasher film very loosely based on [[Literature/IKnowWhatYouDidLastSummer the novel of the same name]] by Creator/LoisDuncan, starring Creator/FreddiePrinzeJr, Creator/SarahMichelleGellar, Creator/JenniferLoveHewitt, and Creator/RyanPhillippe. The screenplay was written by Kevin Williamson, one of the writers of ''Film/{{Scream 1996}}''.

The tale starts with a party and the consumption of too much alcohol, as these stories tend to do, during a beach party after Helen Shivers (Gellar) wins the Croaker County Beauty Pageant. On the way home, however, a drunken swerve of the friends' car leads to the death of a fisherman on the side of the road. The four decide to tell no one, and to forget the whole thing, throwing the body into the ocean. But somebody saw, and the next summer, they start to take vengeance, warning the four with an ominous message: ''[[TitleDrop I KNOW WHAT YOU DID LAST SUMMER]]''. Before long, people start dying, killed by a rain-slicker-clad figure wielding a hook...

The film was followed by two sequels: ''Film/IStillKnowWhatYouDidLastSummer'' (1998) and the straight-to-video ''Film/IllAlwaysKnowWhatYouDidLastSummer'' (2006). For tropes applying to the original novel, see [[Literature/IKnowWhatYouDidLastSummer its own page]].

!!This movie contains examples of:

* AdaptedOut: Barry's mother features prominently in the book, and Helen's parents have a couple of scenes too. Helen's father just appears as an extra, and Barry's mother is barely seen.
* AdaptationDyeJob: Julie is a redhead in the book, and brunette in the film.
* AdaptationExplanationExtrication: A minor example. Elsa in the book is an overweight bitter girl who's jealous of Helen's beauty and easy success - she has to work long hours and still lives at home, while Helen gets a cushy job as a weather girl and is able to afford a nice apartment. In the movie Elsa is just as beautiful, and Helen has a failed attempt at becoming an actress and gets reduced to working in the family department store. So Elsa's jealousy and dislike of Helen isn't really explained.
* AdaptationalAttractiveness:
** Elsa, Helen's sister, is described as very unattractive throughout the book. In the movie, she's just as pretty as Helen is. Elsa was written as plain looking in the script; the director decided that if Helen is gorgeous, Elsa should be too.
** Julie has a moment in the book where she notices her mother going grey-haired, and her hands looking very old. None of this is shown in the film, and her mother looks quite youthful.
* AdaptationalBadass: In the book, Julie is knocked out while Ray fights the killer offscreen. In the film, she helps him fight the killer.
* AdaptationalIntelligence: In the film Julie is said to have been an excellent student whose grades are slipping due to the trauma of the accident. It's the opposite in the book - where Julie was a slacker who had to really work hard to improve her grades after the accident.
* AdaptationalKarma: Helen in the book suffers no negative consequences from the accident - and in fact gets a nice job as the local weather girl, making her able to afford a posh apartment (an impressive feat for a nineteen-year-old). In the film however Helen's attempts at becoming an actress have failed, and she's reduced to working in her parents' department store.
* AgeLift: Barry is a few years older than the gang in the book. Helen is a year above Julie too, who is still in high school. The film makes all the characters the same age.
* AssholeVictim: The fine details are up for debate, but this is a slasher film that actually attempts to justify all the various teenagers getting killed; a hit-and-run probably doesn't deserve a RoaringRampageOfRevenge, but it's not the usual innocent batch of campers either. [[spoiler: It's then revealed that the man they hit had just committed a murder himself, and didn't die when they dumped the body in the sea]].
* BadassLongcoat: The fisherman's raincoat.
* BeautyContest: Helen wins one at the start of the film.
* BeautyIsNeverTarnished: A justified example. The killer cuts off some of Helen's hair while she's asleep, but she reappears for the pageant with it all tidied up. Naturally the killer wouldn't want to give her a reason to miss the parade.
* BigBad: The Fisherman, [[spoiler:aka Ben Willis.]]
* BigBrotherBully: Gender Flipped but Elsa spends most of her screen time mocking or belittling Helen.
* BlackBestFriend: Julie has a sassy black roommate in college called Deb.
* BlackSpot: Julie receives a note saying "I know what you did last summer". [[spoiler: A similar note being found in David Egan's belongings tips her off that he wasn't the man they hit]].
* CantGetAwayWithNuthin: [[spoiler: Barry and Helen]] are the ones who dump the body in the river, and they're the ones who die.
* CondensationClue: Or possibly Cendensation SequelHook: the writing on the fogged-up shower stall glass at the end of the film, Foreshadowing the second film's title.
* DarkSecret: The hit and run that starts the plot.
* DeathByAdaptation: [[spoiler: Nobody dies in the book. Helen and Barry are killed off, as is Helen's sister Elsa]].
* DisposingOfABody: The characters did it last summer.
* ExpositoryHairstyleChange: Julie has curly hair in the intro, but it is unkempt after the accident. Notably in the finale segment, it's curly once again.
* EyeAwaken: The man that protagonists ran over does right after Barry gets on front of his face underwater.
* FallenPrincess: Helen appears to be such. She's implied to be a popular girl at school, and wins the local beauty pageant at the start. There's also cheerleading memorabilia in her room. But her plans to make it as an actress in New York fail, she and Barry split up and she's reduced to working in a department store.
* FanService:
** Jennifer Love Hewitt in that tank top she wears for the final third of the film.
** Sarah Michelle Gellar also walks around wearing hot pants in the second act.
* FinalGirl: Julie, who's a far more of an obvious Final Girl compared to her book self - she gets an AdaptationDyeJob to become brunette, is said to be an excellent student, and takes the moral high ground.
* FreudianExcuse: The killer [[spoiler: is a man who lost his daughter]].
* FromNobodyToNightmare: The Fisherman. [[spoiler: A seemingly normal local man, he became a serial killer after the loss of his daughter]].
* GenreSavvy: When the girls go to visit the family of the man they killed, Helen says "[[Film/TheSilenceOfTheLambs Jodie Foster tried this and a serial killer answered the door.]]"
* TheGloriousWarOfSisterlyRivalry: Helen and Elsa, far more so than in the book. Elsa is more obviously the smart sister - in a prominent position at the family department store, more business savvy and [[SmartPeopleWearGlasses she wears glasses]]. Helen is the pretty sister naturally.
* HooksAndCrooks: The killer carries a gaffing hook.
* HorrorDoesntSettleForSimpleTuesday: All three films take place around the Fourth of July.
* ImpromptuTracheotomy: Max is killed when the Fisherman impales his throat with the gaff hook he took from him moments prior.
* InNameOnly: The original book and the film share only character names and a hit-and-run that sets the plot in motion. Everything else is night-and-day -- the Duncan novel is a mystery/drama [[spoiler:in which none of the main characters die]], while the film is a slasher.
* {{Irony}}: When dumping the body, Barry says to pretend he's a serial killer and they're doing everyone a favour. [[spoiler: It turns out he's ''right'']].
* ItWasHereISwear: Used repeatedly (and relentlessly). The most egregious example is the dead body and 400 crabs stowed in the trunk of one character, only to disappear equally suddenly. Not only does the body and crabs disappear within minutes, but the trunk's carpet is also pristine clean.
* JerkJock: Barry, but more so in the book. He was a football player and goes to college on scholarship. In the movie he's only shown at the gym once.
* {{Meganekko}}: Helen's sister Elsa is shown to be just as beautiful as her, and she also wears glasses when working in the shop.
* MenacingStroll: While going after Helen, the Fisherman chooses to calmly stride after her while she's running away in panic.
* MistakenForMurderer: Julie [[spoiler:wrongly accuses Barry of having been the murderer all along.]]
* NobodyHereButUsStatues: The Fisherman pretends to be a mannequin in Helen's workplace to have a surprise attack on her after she passes him.
* NotQuiteDead: The Fisherman shows signs of movement right before they dump the body. [[spoiler: It turns out he lived after all]].
* OffScreenTeleportation: Max's body vanishes from the trunk of Julie's car. Although given that she ran the rest of the way to Helen's house, had to explain what happened to the other two and then walk back - it does give the killer ''some'' time to move it if he was following Julie from her house. And if Helen's house is further away than we assume from when Julie gets out of the car. [[spoiler: The killer however inexplicably appears out of nowhere to kill Helen when she escapes from the department store]].
* PeekabooCorpse: [[spoiler:While trying to hide from the Fisherman inside his boat, Julie discovers the bodies of Helen and Barry on ice.]]
* PickOnSomeoneYourOwnSize: Intergender example; the crazed fisherman is obsessed with killing Julie James and friends after [[spoiler:they hit him with their car. He got better.]]
* PoliceAreUseless: The inept cop in the first job who dismisses Helen as a hysteric [[spoiler: and ends up getting hooked himself.]]
* PunkInTheTrunk: Julie discovers the crab-covered body of Max in the trunk of her car. After she brings her co-conspirators to see it, it has disappeared.
* RedHerring:
** [[spoiler: When Julie tells Helen about the note, there are a couple of shots of Elsa looking at them. Elsa is also said to have been in David Egan's class at school. In the book Elsa is also a suspect]].
** Max is initially assumed to be behind the note, as the only person the teens saw that night.
** [[spoiler: Missy is also introduced in a way that makes her seem like she could be a suspect too]].
* TheReveal: [[spoiler: The killer is Ben Willis (the guy the group actually hit) and not David Egan (who they thought they hit, and who Ben actually killed) or someone trying to avenge him.]]
* RoaringRampageOfRevenge: The Fisherman after he's left for dead.
* RuleOfSymbolism: The accident and cover-up symbolise the loss of innocence from childhood to adulthood. The protagonists are teenagers graduating from high school, and the plot takes place after they've spent a year trying to live as adults. Helen notably has become a FallenPrincess, Julie was once a straight-A student whose grades are slipping, and Barry was once the BigManOnCampus that ends up in hospital. The characters lamenting how they can't go back to how their lives were before the accident parallels how they can't become innocent again.
* SacrificialLamb: Max, whose death was added in re-shoots, after filmmakers realised they needed to show that the killer posed a threat.
* SassyBlackWoman: Julie's college roommate Deb.
--> "Get your white as death, chalky corpse in that car ''now''."
* SettingUpdate: The book was set in the 70s, and a plot point was one character being a Vietnam veteran. The film is updated to the 90s.
* ShirtlessScene: Barry gets one after taking a shower at a gym where he finds his own note from the Fisherman.
* StrangerBehindTheMask: [[spoiler:The twist is that David Egan is in fact ''not'' the man the teens hit with the car. It's actually the man who murdered him - though this is foreshadowed earlier in the film]].
* TimeSkip: After the climax, the ending of the film happens ''"One year later..."''
* TraumaticHaircut: The killer cuts off some of Helen's hair while she's asleep.
* TrueBlueFemininity: The dress that Helen wears in the Croaker Queen pageant is a light blue.
* VillainBall: The Fisherman sure does pass up a lot of opportunities to kill those teens. Somewhat justified, as his intent is not only to kill them, but to make them squirm and be afraid. Still, [[spoiler:Willis' quest for revenge threatens to expose his murder of David Egan, which he would've been clear of completely thanks to the teens]].
* WeUsedToBeFriends: After visiting Missy's house, Julie and Helen have this exchange in the car.
--> '''Helen:''' What ever happened to us? We used to be best friends.
--> '''Julie:''' We used to be a lot of things, Helen.

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