Praying Mantis (1982)
A middle-aged professor's young bride and his assistant plan to commit a double murder disguised as a "Crime Passionel", but discover too late that one of their intended victims has become a fellow conspirator.
A middle-aged professor's young bride and his assistant plan to commit a double murder disguised as a "Crime Passionel", but discover too late that one of their intended victims has become a fellow conspirator.