Twitch of the Death Nerve

A Bay of Blood Italian Ecologia del delitto also known as Twitch of the Death Nerve, Blood Bath and Reazione a catena, is a 1971 Italian horror film directed by Mario Bava. Bava cowrote the screenplay with Giuseppe Zaccariello, Filippo Ottoni and Sergio Canevari, with story credit given to Dardano Sacchetti and Franco Barberi. The film stars Claudine Auger, Luigi Pistilli and Laura Betti. Carlo Rambaldi created the gruesome special makeup effects. The story details the simultaneous murderous activities of several different characters as they each attempt to remove any human obstacles that stand in the way of an inheritance of a bay.

At night in her bayside mansion, wheelchairbound Countess Federica Isa Miranda is attacked and strangled to death by her husband Filippo Donati Giovanni Nuvoletti. In turn, an assailant suddenly stabs him to death. Donatis corpse is then dragged to the bay. The police find what they believe to be a suicide note written by the Countess. Donatis murder goes undiscovered.Real estate agent Frank Ventura Chris Avram and his lover Laura Anna Maria Rosati plot to take possession of the bay. They had arranged with Donati to murder his wife after she had refused to sell her house and property to them. To finalize their scheme, Ventura needs Donatis signature on a set of legal documents. They have no idea that Donati has been killed. ........

Source: Wikipedia