Nightmare Castle (Alpha)

Muriel and David are caught in an adulterous affair by her sadistic husband Stephen, who subjects the couple to horrific tortures in his laboratory. He viciously executes them, but they are far from being disposed of. The unholy lovers return from the grave to wreak horrifying revenge on the scheming doctor and Muriel's psychotic twin sister , Jenny.

Originally released as Amanti d'Oltretomba, this incessantly gruesome film draws high praise from fright-fest connoisseurs.