Spanish title: Detrás del silencio
English title: Knife of Ice
The sweet singer Jenny Ascot visits her cousin Martha Caldwell in the Pyrenees, who has long been mute following a shock after an accident. Martha appears thrilled to see her cousin again but, on the journey to home, both are terrified by the hallucinatory gaze of a mysterious man. Caldwell house is immersed in mists and during the night Jenny is attacked and murdered. The police are convinced it is the work of a satanist maniac, but it will be Martha who puts them on the right track.