Lois Duncan Steinmetz (April 28, 1934 – June 15, 2016) was a prolific young adult writer, well known for her suspense novels. Several of her novels, ''Film/HotelForDogs'', ''Literature/IKnowWhatYouDidLastSummer'', ''Literature/KillingMrGriffin'', ''Summer of Fear'' and ''Stranger with My Face'', have been adapted to {{film}} or [[LiveActionTV television]], with ''I Know What You Did Last Summer'' probably being the best known.

Having been a writer since TheFifties, her style has changed much over the years, with some of her [[Literature/AGiftOfMagic earlier books]] possibly being even a little bit sexist in tone.

!! Her works include:

* ''Literature/AGiftOfMagic''
* ''Literature/DownADarkHall'' (film adaptation: ''Film/DownADarkHall'')
* ''Hotel for Dogs'' (film adaptation: ''Film/HotelForDogs'')
** ''News for Dogs''
** ''Movie for Dogs''
* ''Literature/IKnowWhatYouDidLastSummer'' (film adaptation: ''Film/IKnowWhatYouDidLastSummer'')
* ''Stranger with My Face''
* ''Summer of Fear'': The LiveActionAdaptation is also known as ''Stranger in Our House'', and stars [[Film/TheExorcist Linda Blair]].
* ''Literature/KillingMrGriffin''
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!! Other works by Lois Duncan contain examples of:

* AdultsAreUseless: In several of her books. Most blatantly in ''Gallows Hill'', in which Sarah tries to report the harassment she faces at school, but her mother is too wrapped up with her boyfriend to care and the school staff does not take her seriously or sees her as the instigator.
* TheAgeless: In ''Locked in Time'', Lisette and her children have eternal youth but not eternal life.
* BathroomStallOfOverheardInsults: In Creator/LoisDuncan's ''Don't Look Behind You,'' April/Valerie ducks out of the movie the kids are seeing and visits the bathroom. While she's in there, two girls from the group come in gossiping about her, take the stalls on either side of the one she's in, and continue to talk. Despite the theater only showing one movie and having one set of restrooms, and despite a stall being occupied when they come in right after they saw April/Valerie ''leave the single theater,'' it never occurs to them that they might want to be discreet.
* BurnTheWitch: Averted in ''Gallows Hill'', which accurately depicts hanging as the form of execution favored at the Salem Witch Trials.
* DisownedAdaptation:[[invoked]] She despised the film adaptation of ''Film/IKnowWhatYouDidLastSummer'', which was InNameOnly and turned the mystery story into a SlasherMovie. It hit uncomfortably home for her, as her own teenage daughter had been murdered.
* GrandTheftMe: In ''Stranger With My Face'', identical twin sisters Laurie and Lia are separated in infancy when Laurie is adopted and Lia is not. Lia learns astral projection and uses it to visit Laurie when the girls are seventeen, and teaches Laurie to do it too -- in order to trick Laurie into this trope.
* HeroicBSOD: One of the young protagonists in ''Ransom'' goes into one of these after failing to SaveTheVillain, imagining that he can still see the villain's screaming face. (An unusual reaction for a thriller hero, perhaps, but after all, this is just a high school kid who's never even seen someone die before.)
* InWithTheInCrowd: In Lois Duncan's books, this is definitely ''not'' a good thing, as the in crowd tends to range anywhere from hopelessly shallow {{Jerkass}}es, with NoSympathy for the protagonist's problems, to actually malevolent. The latter proves true in ''Killing Mr. Griffin''.
* MyGrandsonMyself: In ''Locked in Time'', Lisette Berge occasionally explains that the reason older people seem to know her is that she looks exactly like her mother, who was also named Lisette Berge. Lisette's stepdaughter Nora, however, realizes that this can't be the case because "Berge" was supposed to have been Lisette's name from her first marriage, so her mother would have had a different one.
* NamesToRunAwayFromReallyFast: Despite Duncan's recurring themes of suspense and horror, only one of her antagonists bears such a name: Mike Vamp, the hit man from ''Don't Look Behind You'', whose name is evocative of vampires. Lampshaded in the book.
* NoGoodDeedGoesUnpunished: In ‘’Don’t Look Behind You", April’s father acts as a confidential informant for the government, leading his entire family to be placed in Witness Protection. As a result, both his and his wife’s careers are ruined, his daughter’s athletic and college aspirations are crushed, and they can’t take a simple family vacation without putting themselves in danger.
* NotGrowingUpSucks: Josie in ''Locked in Time'' has to live forever as a preteen, both physically and emotionally. As a result, she's moody, temperamental, and constantly trying to make herself look older.
* NotHimself: In ''Stranger With My Face'', protagonist Laurie's body is stolen by her identical SeparatedAtBirth twin, Lia. The only people who notice that anything's amiss are her adoptive little sister, who spots that Laurie is acting out of character, and Laurie's boyfriend, who knows the whole story and suspects that Lia might have done exactly what she did.
* {{Reincarnation}}: ''Gallows Hill'' is of the "past events play out in the present" subtype, but with a strong emphasis on ScrewDestiny--the protagonist was one of the girls whose accusations kicked off the Salem witch trials, and she has no intention of repeating the slaughter.
* ScrewDestiny: ''Gallows Hill'' looks at this by way of {{Reincarnation}}, as the events of the Salem witch trials play out again in the present, but one of the girls whose accusations started the trial refuses to play her part. [[spoiler:This time around, she manages to redeem herself and [[EverybodyLives keep everyone alive]].]]
* SeparatedAtBirth: In ''Stranger with My Face'' the main character was adopted at birth, but her parents decided not to take her twin sister because ''they could sense her evil''. The other twin grows up to come and ruin the heroine's life, using, of all things, astral projection.
* SettingUpdate: In the 2000s, she had her work undergo a bit of an update - changing the slang and clothing descriptions to seem more modern. She would also have mentions of cell phones, and simply find reasons for the characters not to have them when they would have broken the plot.
* TheSociopath: A favorite reoccurring villain in her books, particularly Mark Kinney of ''Killing Mr. Griffin'', who is explicitly labeled a psychopath, Larry in ''They Never Came Home'', Sarah in ''Summer of Fear'', Mike Vamp in ''Don't Look Behind You'', and Lia from ''Stranger with My Face''.
* StrawFeminist: Irene Stark in ''Daughters of Eve''. A champion of female empowerment, she quickly degenerates into DoesNotLikeMen, BlackAndWhiteInsanity, and [[HeWhoFightsMonsters She Who Fights Monsters]]. A reader comment characterizes Stark as a feminazi, with Duncan herself expressing agreement.
* TeenHorror: Her horror novels frequently focused on teenagers as the protagonists dealing with various terrifying threats.
* ThereAreNoTherapists: Grimly subverted in ''Gallows Hill.'' DomesticAbuse victim Mrs. Lamb is seeing a church counselor to cope with the situation, but her husband refuses to join her because ''he's'' a counselor himself and, [[SarcasmMode due to his expertise in the matter,]] believes that it's NeverMyFault. The protagonist is understandably unwilling to see him for counseling when her own problems arise.
* UnreliableNarrator: Invoked in ''The Twisted Window''.
* WhoWantsToLiveForever: Josie, before of her aforementioned eternal-preteen status, has this attitude. [[spoiler: Gabe is implied to feel the same way, as he kills himself and Lisette at the end, although that may also have been because of genuine feelings for Nore.]]

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