Several young girls were killed. Policeman Matthaei travels to the region where it happened and searches a child that looks similar to the ones that were murdered. He finds one and stays with her and her mother, not telling them that he is waiting for the killer to start his bloody work.
This film is not currently playing on MUBI but 30 other great films are. See what's now showing
Girl-meeting sequence will be reference to Pennywise the Dancing Clown on IT. Don't forget The Pledge connection. Best novel adaptation ever (!) The thing is, they have a novelist but script is original and his first screenplay. Amazing!
I love Sean Penn's adaptation of the same source material, The Pledge, starring Jack Nicholson as the retiring police officer who refuse to close a child murder case. This one is the original swiss-german adaptation; it's not as bleak as Penn's version, but just as engaging and well told. Gert Fröbe is an effective villain, and Ladislao Vajda makes the film look and sound as it was directed by Hitchcock.
Might not have aged well, but Fröbe is incredibly menacing as a pedophile and Dürrenmatt was one of the best German post-war writers. Check out "Das Versprechen", the "novelization" of this film with a twist ending.