While spending the summer on Fire Island, Peter and Dan, two adolescent boys from upper-middle-class families, meet Sandy, a young girl who has found a wounded seagull on the beach. After the boys remove a fishhook from the bird’s throat, the three youngsters become fast friends and spend all their time together, swimming, boating, smoking marijuana and cautiously experimenting with their awakening sexual impulses during visits to a movie house on the mainland.
One afternoon they are joined by Rhoda, a plump 15-year-old who is anxious to make friends. When the boys discover that Sandy has brutally killed the gull for biting her, Peter begins to shift his attention to Rhoda. Finding it fun to taunt Rhoda about her inexperience with boys, Sandy gets Peter and Dan to persuade the reluctant Rhoda to take her place, and all four go to a restaurant to meet the shy Puerto Rican, Anibal.
To Rhoda’s embarrassment, Sandy, Dan, and Peter get the man drunk and abandon him to three local bullies. Although Rhoda rebukes Peter for his behavior, she succeeds only in alienating him, and he goes off with Sandy and Dan for a picnic in the woods. Dan’s plan of proving his manhood to Sandy is ruined when Rhoda tags along.
Irritated by Rhoda’s intrusion into their clique, Sandy removes her bikini top and dares Rhoda to do the same. Disgusted, Rhoda tries to leave, but Sandy goads the boys into holding her back. The frightened girl appeals to Peter for help, but he joins Sandy in pinning Rhoda to the ground while she is savagely raped by Dan. Following the assault, the three leave; Sandy and Dan return to the beach while Peter hesitates on a sand dune near Rhoda.