Jane, Pamela Franklin and Cathy, Michele Dotrice, are two young nurses from Nottingham who set off on a cycling holiday through rural France. Over a busy lunch at a crowded restaurant, Cathy spots a handsome man drinking alone at a nearby table. Once they part ways, the man also leaves the cafe on a Lambretta scooter. A country road framed by fields and hedges becomes a quiet stage for their brief encounter: he passes them on his scooter, and a little later they ride past him as he rests near a cemetery.
As they roll into a small village, they meet him again. Cathy, tiring of the cycling, decides to sunbathe, while Jane agrees to pause briefly but the two quarrel over their itinerary, and Jane presses on alone. She reaches a rural roadside cafe where the proprietor, Madame Lassal, warns her that the area can be dangerous for a lone traveler. Meanwhile, Cathy, still basking, grows unnerved and feels watched; when she tries to leave, she discovers the wheel of her bicycle has been destroyed, and moments later she is confronted by an unseen assailant.
Feeling guilty for leaving Cathy behind, Jane backtracks to the sunlit spot. She finds no trace of Cathy except for her camera lying in the grass. Moments later, the man from the restaurant stops by again on his scooter and introduces himself as Paul. Jane explains she is looking for Cathy, and Paul offers Jane a ride back to the village, hoping Cathy may have gone there. While she questions locals, she learns of an unsolved rape and murder of a young woman that occurred in the town three years earlier, described by an English schoolmistress, Clare Kelly, as
> "quite a scandal".
Paul then rides into the woods to search for Cathy. Unable to locate the gendarme, Jane persuades the English schoolmistress to drive her part-way to meet him and report Cathy's disappearance. En route, the schoolmistress recounts that the old case occurred in the same wooded area where Cathy vanished, a detail that deepens Jane's unease. When she returns to the roadside cafe to seek help from Madame Lassal, the proprietor again urges her to leave the area. Jane crosses paths with Paul once more, who reveals he once worked for the Surete and has been privately researching the murdered woman. A heated clash erupts when Jane discovers Paul has taken Cathy's film as evidence. Convinced Cathy may be hurt, she parts ways with him.
She finally locates the gendarme's residence and explains what has happened, prompting the gendarme to go investigate the scene, leaving Jane alone inside. Paul arrives at the house, but Jane refuses to open the door. When he forces his way in, Jane flees into the woods and stumbles upon an abandoned trailer park. Hiding in a camper, she discovers Cathy's corpse. Paul corners Jane in the woods, but she strikes him in the face with a rock. At the edge of the trailer park, she finds the gendarme, hopeful that he will help her, only to discover he is the perpetrator, who begins to fondle her and then sexually assaults her. Jane fights back, and the assault is interrupted when an injured Paul arrives and strikes the gendarme with a heavy branch.
