i know what you did last summer summary

In an unnamed town, high school senior Julie James receives a sinister note from an elusive stalker telling her, "I Know What You Did Last Summer", referring to the previous year when Julie, her boyfriend Ray Bronson, Ray's best friend, Barry Cox, and Barry's girlfriend, Helen Rivers, accidentally killed a young boy named David Gregg after driving home from a party in the mountains to celebrate Ray and Barry's high school graduation. The four made a vow to never mention it to anyone, and drifted apart, Barry going to the local college, Helen dropping out of school, Ray taking off for California and Julie continuing to attend school. Fearful, Julie visits Helen, and informs her about the note. Barry is called but he assures the girls it is a prank and nothing more, as if anyone did know about their crime, they would inform the authorities and not write notes. The girls buy it, and Ray returns home to Julie, but is disheartened when she reveals she is now dating a fellow named Bud, and no longer wants to continue their relationship.
It is revealed that shortly after the night of the incident, Helen was chosen via a beauty contest to be the Channel Five Golden Girl, meaning she would be the studio's new television personality, much to the fury of Elsa, her sullen, envious and plain-looking older sister. At the Four Seasons, a luxury apartment complex where she lives, Helen is suntanning when she meets a boy, Collingsworth "Collie" Wilson, just out of the army. After she is done talking to Collie, she goes to her apartment and finds a magazine cut out of a boy riding a bicycle taped to the door.
Meanwhile, Ray is at his house and finds that he has been sent a newspaper clipping though the mail about the boy he, Barry, Helen, and Julie had killed last summer, David Gregg .
On Memorial Day, Barry receives a call. After he hangs up, he walks out of the University frat house where he leaves to meet the person who had called him. As it is dark, he does not see too well and