I Know What You Did Last Summer is a 1997 American slasher film directed by Jim Gillespie, written by Kevin Williamson, and starring Jennifer Love Hewitt, Sarah Michelle Gellar, Ryan Phillippe, and Freddie Prinze Jr., with Anne Heche, Bridgette Wilson, and Johnny Galecki appearing in supporting roles. Loosely based on the 1973 novel of the same name by Lois Duncan, the film centers on four young friends who are stalked by a hook-wielding killer one year after covering up a car accident in which they were involved. The film also draws inspiration from the urban legend known as the Hook.
After having written Scream (released in 1996), Williamson was approached to adapt Duncan's source novel by producer Erik Feig. Where Williamson's screenplay for Scream contained prominent elements of satire and self-referentiality, his adaptation of I Know What You Did Last Summer reworked the novel's central plot to resemble a straightforward 1980s-era slasher film. Shot on location in both California and North Carolina in the spring of 1997, I Know What You Did Last Summer was released theatrically in the North America on October 17, 1997. It received varied reviews from critics but was commercially successful, grossing $72 million domestically, and remaining at number 1 on the U.S. box office for three consecutive weeks. It would go on to gross an additional $53 million in other markets, making for a total of over $125 million in international box office returns. It also was nominated for and won multiple awards.
The film was followed by two sequels, I Still Know What You Did Last Summer (1998) and the straight-to-DVD release I'll Always Know What You Did Last Summer (2006). Though the former film has a continuation of the plotline established in its predecessor, the latter film establishes a new plotline and does not star any cast members from the previous two installments. I Know What You Did Last Summer has also been parodied and referenced in popular culture, and credited alongside Scream with revitalizing the contemporary slasher film in the late-1990s.