The book I Know What You Did Last Summer is a young adult thriller novel written by Lois Duncan, first published in October 1973 by Little, Brown and Company
. The story is set in the fictional town of Silver Springs and follows four high school seniors-Julie James, Ray Bronson, Barry Cox, and Helen Rivers-who are involved in a hit-and-run accident that kills a young boy named David Gregg. After anonymously calling an ambulance, they make a pact never to reveal their involvement. A year later, their secret is threatened when Julie receives a note saying, "I know what you did last summer," leading to a suspenseful unraveling as they try to outsmart a killer seeking revenge
. The novel was updated and reissued in 2010 with modern elements such as cell phones and updated cultural references, including changing a character's war from Vietnam to Iraq
. Unlike the 1997 film adaptation, the book begins almost a year after the accident without flashbacks, focusing more on the psychological aftermath and the characters' struggles with guilt and fear
. Lois Duncan was well known for her suspense novels for teenagers, and I Know What You Did Last Summer is among her most famous works, having inspired the classic horror film of the same name
. The book is praised for its deep exploration of flawed characters and the tension stemming from their dark secret
. In summary, I Know What You Did Last Summer is a suspenseful young adult novel about four teens dealing with the consequences of a fatal accident and the deadly threat that follows when their secret is exposed. It combines elements of thriller and psychological drama, making it a seminal work in young adult suspense fiction
