Peter Ruric, also widely known by his pseudonym Paul Cain, was an influential American author and screenwriter. He is best remembered for his hardboiled novel Fast One, a seminal work in the pulp fiction genre that influenced writers like Raymond Chandler. As a screenwriter, Ruric contributed to several films, most notably co-writing the screenplay for the 1934 horror classic The Black Cat. His writing is characterized by its lean, rapid-fire prose and grim, unsentimental depiction of the criminal underworld.