La cruz del diablo (translation: The Devil's Cross) is a 1975 Spanish horror film directed by John Gilling (his first film since he left Hammer Films in 1967) and starring Carmen Sevilla, Adolfo Marsillach, Ramiro Oliveros and Emma Cohen. Its plot concerns a hashish-smoking British writer who travels to Spain to visit his sister, only to discover she has been murdered by a satanic cult.

Plot

A hashish-smoking British writer, Alfred Dawson (Ramiro Oliveros), has been suffering from vivid nightmares. The subjects of the recurring nightmares are a marauding cult of undead medieval Knights Templars on horseback tormenting a woman in white, who cries for help. He is unsure whether the dreams are caused by the hashish, or are some sort of vision. Alfred's sister Justine, fearing she is in danger, asks him to visit her in Spain, where she lives with her wealthy Spanish husband. However, when Alfred arrives, he discovers that she has been murdered. He vows to find the murderer, even as it leads him and his companions to the fearful region of the Devil's Cross and the ruins of the Templars' castle.