Two attractive young women decide to spend their vacation cycling on isolated roads in countryside where they don't speak the local language. Jane and Cathy might be forgiven when we consider the two English girls have chosen to vacation in France but we can anticipate little good fortune in a movie called And Soon the Darkness with a screenplay co-written by Terry Nation, creator of the Daleks. This 1970 film feels more like television than cinema with a story featuring endless baits and switches, unremarkable but serviceable visuals, and average performances. It's a mystery with a lot of red herrings that plays fair for the most part but is more satisfying for its escalating sense of dread.
In all this empty space, these desolate stretches of road between isolated villages, the two young women stop to rest by a little patch of woods where a girl just like them had been raped and murdered a few years ago, something Jane (Pamela Franklin) learns much later. After a little while, Jane wants to move on but Cathy (Michele Dotrice) wants to stay and doze a bit longer. Somehow this turns into a big fight--and a line I suspect was improvised as Jane, moving her bike, says, "Get your great fat legs out of the way!" and Cathy can't suppress a grin. But in any case, the girls separate, Jane goes on to the next village and Cathy says she'll catch up. Of course, she never does.
As Jane becomes increasingly worried, going back and forth between two villages and the spot where they'd stopped, the film gives us a series of suspects who all seem suspicious in each their own way--a man claiming to be a detective who'd investigated the previous murder (Sandor Eles), a Gendarme (John Nettleton) an innkeeper hastily warns Jane to beware of, an English schoolmistress who invites Jane to stay with her.
When we do learn at the end who the villain is, one or two things done by the suspects meant to mislead our suspicions don't add up. But for the most part, the film succeeds in a suspense created by a vulnerable, fish out of water character who suddenly finds herself surrounded by strangers who are all sinister in one way or another.