Why the Author of I Know What You Did Last Summer Hated the Film Adaptation

Undeniably, one of the most recognizable and popular horror flicks of the 1990s is the ’97 knockout I Know What You Did Last Summer, a hair-raising slasher staple that centered on four North Carolina teenagers who, after accidentally causing the death of a pedestrian, find themselves being stalked and terrorized by a violent and dangerous assailant one year later. The blockbuster hit famously starred Jennifer Love Hewitt, Sarah Michelle Gellar, Freddie Prinze Jr., and Ryan Phillippe, and was able to capitalize on the resurgence of horror movies and the success of fellow slasher Scream.

While audiences all across the world flocked to see the brooding teens fight for their lives, author Lois Duncan, who wrote the novel on which the film’s screenplay was based, was far less enthused by the silver screen adaptation. The decorated writer was extremely upset that her young adult novel was given a gruesome and gory makeover by Hollywood, prompting Duncan to become outspoken over the slasher film as a result. Let’s dive in and explore why Duncan hated I Know What You Did Last Summer.

I Know What You Did Last Summer Is an Iconic Slasher Staple of the 1990s

The late 1990s brought forth a resurgence in popularity for the spine-tingling slasher genre, with Wes Craven’s electrifying hit Scream kicking off a renewed interest in horror films during the influential decade. Kevin Williamson (Dawson’s Creek, The Vampire Diaries) notably wrote the screenplay for the Craven masterpiece and followed up the box office knockout by helping create a big-screen adaptation of Lois Duncan’s suspense novel I Know What You Did Last Summer, hoping to mirror the success and impact of Scream.

Loosely based on the chilling Duncan tale, the ominous picture famously follows four high school friends who are mercilessly terrorized by a menacing, hook-wielding killer after seemingly causing the death of a pedestrian the year prior, and together, the teenagers must fight for their lives and figure out who the identity of their mysterious aggressor is. I Know What You Did Last Summer featured a sensational ensemble cast of some of Hollywood’s greatest up-and-comers, with the adaptation touting the talents of Jennifer Love Hewitt, Sarah Michelle Gellar, Freddie Prinze Jr., and Ryan Phillippe.

Hewitt headlines the horror flick and stars as Julie James, who, along with her devoted boyfriend Ray Bronson (Prinze Jr.) and friends Helen Shivers (Gellar) and Barry Cox (Phillippe), attend a beauty pageant Helen enters and subsequently wins on the Fourth of July. After celebrating the exciting feat, the group end up becoming involved in a hit-and-run and decide to dump the body into the sea, swearing to never speak of the horrific incident ever again. Exactly one year later, Julie receives a threatening letter with an unsettling warning that reads, “I know what you did last summer!” setting off a frightening chain of events that leads to mayhem and murder.

Author Lois Duncan Loathed the I Know What You Did Last Summer Film

In hopes of capitalizing on the slasher film craze as well as the overwhelming success of Scream, Columbia Pictures rushed I Know What You Did Last Summer into production, and Williamson had to write the screenplay quickly, retooling crucial elements of Duncan’s novel while also drawing inspiration from “The Hook” urban legend in addition to fellow slashers The House on Sorority Row and Prom Night. Director Jim Gillespie would later express how he did not feel the script resembled a “slasher horror movie” and that instead, he simply saw it as “a really good story” containing a meaningful morality lesson; author Lois Duncan did not share Gillespie’s sentiment.

The award-winning author loathed the 1997 Hollywood adaptation and was upset that her young adult novel was transformed into a bloody and brutal slasher film on the silver screen and felt it did not honor the subject source. In a 2002 interview, Duncan once said, “I was appalled when my book, I Know What You Did Last Summer was made into a slasher film. As the mother of a murdered child, I don’t find violent death something to squeal and giggle about.” The writer’s daughter Kaitlyn was just 18 years old when she was shot and killed in her car on July 16, 1989, with the authorities calling it a random drive-by but Duncan believing there was more to the crime.

She would go on to write the nonfiction book Who Killed My Daughter? in 1992, which detailed her beloved daughter’s unsolved murder and led to the author stepping away from the horror and thriller genres. Duncan had sold the rights to I Know What You Did Last Summer for $150,000 and thus “gave up creative control over the project,” though she also received royalties from the box office profits. After being invited to read the script and visit the set, Duncan was appalled by the creative liberties taken and refused to attend the premiere. She would later declare to the Daily Press upon the film’s release:

“They optioned my story, not my soul. There is no way I want to be part of desensitizing kids to violence and turning murder into a game to see who can scream the loudest.”

I Know What You Did Last Summer Is an Influential & Enduring Horror Franchise

Despite Lois Duncan’s valid and profoundly sad personal reasons for detesting the big screen adaptation, I Know What You Did Last Summer nonetheless became a massive commercial triumph, topping the box office for three consecutive weeks and going on to gross $125.3 million worldwide against a $17 million budget. The unforgettable slasher had moviegoers on the edge of their seats as they rooted for the four troubled teenagers to survive against the sadistic, vengeance-seeking antagonist, and went on to win two Blockbuster Entertainment Awards while earning a Saturn Award nod for Best Horror Film.

I Know What You Did Last Summer also became a pop culture phenomenon, parodied in the comedy Scary Movie while spawning the direct 1998 follow-up I Still Know What You Did Last Summer as well as both a standalone sequel and short-lived 2021 television series. In February 2023, a legacy sequel was officially announced to be in development, with both Jennifer Love Hewitt and Freddie Prinze Jr. set to reprise their respective roles, with the highly-buzzed about installment picking up where the second film left off. The sequel will be directed by Jennifer Kaytin Robinson and will feature the additional talents of stars like Madelyn Cline and Jonah Hauer-King. It is slated to hit theaters on July 18, 2025. Stream I Know What You Did Last Summer on Tubi.