In the eerie Mexican horror film La Castillo de la pureza (1973), a psychotic patriarch forbids his family from leaving the grounds of their crumbling estate for fear of imagined threats from the outside world. Cooped up without exposure to society, the madman (Arturo Beristáin) labors to invent a cruel new poison capable of killing anyone who trespasses on his property. Clearly the man’s a nut job, but you can understand why he might not want the townspeople scoping his delectable wife, played by the oft nude Diana Bracho.