Inside the Story Behind I Know What You Did Last Summer — What Lois Duncan Really Thought About the Movie
If you’re a fan of ’90s horror flicks, you’ve probably heard of I Know What You Did Last Summer. It’s a cult classic for sure — the kind of movie that gave us one of the iconic masked killers in horror alongside legends like Jason Voorhees and Michael Myers. But did you ever stop to wonder what the original author thought of the film? Spoiler alert: Lois Duncan wasn’t exactly thrilled.
The Original Story vs. The Movie Twist
Lois Duncan wrote I Know What You Did Last Summer back in 1973. The book’s plot is pretty straightforward — four teenagers accidentally kill a cyclist, cover it up, and then a year later, someone starts blackmailing them. It’s a tense thriller, grounded in real emotions and suspense.
Fast forward nearly 25 years, and screenwriter Kevin Williamson takes the reins for the 1997 adaptation. His big addition? The introduction of the villain “The Fisherman,” a masked killer stalking the teens. This was a huge departure from Duncan’s original story — turning the novel into a full-on slasher movie with jump scares and violent chases. Williamson told Screaming and Conjuring — a new book about the modern horror movie renaissance — that he wanted to create a killer as memorable as Jason or Michael Myers. Coming from a fishing community in North Carolina, he actually went to his dad to understand how a fisherman’s gear worked, hoping to add authenticity to the movie’s murder scenes.
"My dad showed me the A-frame on the boat and how someone could be jerked up to the top," Williamson shared. “But then he said, ‘Kevin, that would never happen.’ I told him, ‘Yes, but it’s in the movie, Dad.’”
That little anecdote gives you a peek into how much creative liberty was taken. Williamson even rewrote scenes, including Johnny Galecki’s on-screen death, and tweaked the movie’s ending — choices that paid off with fans and turned the movie into a cult classic.
Lois Duncan’s Harsh Reality
Here’s where it gets intense. Duncan was not happy with what became of her book on the big screen.
According to an excerpt from Clark Collis’ upcoming non-fiction book Screaming and Conjuring: The Resurrection and Unstoppable Rise of the Modern Horror Movie, Duncan was “unaware” of the changes until she actually saw the finished film. And when she did, she was “horrified” by the sensationalized violence.
Why such a strong reaction?
Several years earlier, Duncan’s teenage daughter, Kaitlin Arquette, was tragically murdered. In 1989, Kaitlin was shot while driving home from a friend’s house, just after graduating high school. The loss was devastating for Duncan, and it gave her a painfully personal understanding of real violence.
“To have people screaming and laughing about it did not go down well,” Duncan revealed during a 2010 Q&A with fellow young adult author Barry Lyga, as noted in the book.
So while I Know What You Did Last Summer the movie was fun for some, it struck a nerve for Duncan. The film’s over-the-top slasher elements felt insensitive against the backdrop of her own real-life grief.
The Silver Lining
Despite her disapproval of the movie’s tone, Duncan admitted there was a silver lining. The film’s release made her original novel — and several of her other works — suddenly popular again.
“It was like getting a rebirth, but in a very strange way,” she said.
For an author whose career had been mostly steady, this newfound attention was a double-edged sword. The popularity brought new readers to her backlist, but the violent, sensationalized film left a bitter taste.
Justice Served — Years Later
The tragedy of Kaitlin’s murder haunted Duncan until her death in 2016. It wasn’t until July 2021, five years after Duncan passed away, that a breakthrough happened.
Paul Apodaca confessed to three rapes and three murders, including the killing of Kaitlin Arquette, according to Rolling Stone. The man was sentenced to 45 years in prison in January 2024, bringing some measure of closure to the family.
New I Know What You Did Last Summer Sequel Coming Soon
Just days after the excerpt from Screaming and Conjuring was released, the new I Know What You Did Last Summer sequel hit theaters. The film brings back Freddie Prinze Jr. and Jennifer Love Hewitt as their iconic characters Ray Bronson and Julie James.
The new cast includes fresh faces like Chase Sui Wonders, Madelyn Cline, Sarah Pidgeon, Tyriq Withers, and Jonah Hauer-King, ushering in a new era for the franchise. Fans of the original will be excited to see the legacy continue, though hopefully with a tone a little closer to Duncan’s original vision.
Why This Story Matters
Lois Duncan’s experience highlights a key tension in adapting books to movies, especially in the horror genre: balancing artistic vision with entertainment value. It’s easy for filmmakers to ramp up the violence and scares to please audiences craving thrills, but for authors — especially those with personal ties to tragedy — it can feel exploitative or disrespectful.
The story also serves as a reminder that behind every horror story on screen, there are often real people and real pain that shouldn’t be overlooked.
Quick Takeaways:
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Lois Duncan, author of I Know What You Did Last Summer, was deeply disturbed by the 1997 movie’s violent and sensationalized approach.
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The movie added the “Fisherman” killer, a big departure from Duncan’s original novel’s plot.
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Duncan’s personal tragedy — the murder of her daughter Kaitlin in 1989 — gave her a firsthand understanding of real violence, making the movie’s tone painful.
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Despite her horror at the film’s changes, Duncan was glad it brought renewed interest in her books.
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The killer’s murder was solved years later, bringing some peace to Duncan’s family.
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A new sequel movie just came out, continuing the story with original cast members returning.
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