An adaptation of a British thriller novel, written by the crime writer Audrey Erskine Lindop. The 14-year-old schoolgirl Wynne Kinch has a crush on her older stepbrother George, who is in his early 30s. She starts spying on George, but she notices some unsettling details about her beloved stepbrother. He has unexplained scratches on his back, and there was blood on a jumper which he recently discarded. Wynne worries that George might be the same person as a local serial killer who preys on teenage girls. Wynne's best friend Corinne flirts with George during a picnic. George responds by angrily pinning down Corinne and calling her a "mini-tart". Corinne vanishes after going on a date with a mysterious suitor, and the worried Wunne searches for her. She finds Corinne's dead body at the former residence of the Kinch family. Wynne thinks that George killed her best friend, before being confronted by the actual killer.