Paul Cain was the pen name of George Caryl Sims (1902-1966), an American pulp writer and screenwriter whose small body of work left a lasting mark on hard-boiled crime fiction. Writing as Paul Cain, he became associated with Black Mask, the magazine that helped define the American hard-boiled tradition. His fiction is known for its violent momentum, emotional coldness, stripped-down prose, and refusal to soften the world it depicts. Cain wrote only one novel, Fast One, but its reputation has grown steadily among readers and critics of pulp crime, noir fiction, and early twentieth-century American gangster literature.Cain also worked in Hollywood under the name Peter Ruric, contributing to screenplays including the 1934 horror film The Black Cat. His fiction often follows men on the wrong side of the law rather than conventional detectives, giving his work a darker and more fatalistic edge than many crime stories of the period. Fast One, first serialized in Black Mask and then published as a novel in 1933, remains his central achievement: a cold, rapid, violent masterpiece of the ultra-hard-boiled school and a key title for readers interested in Black Mask fiction, American noir, Los Angeles crime fiction, and the development of modern hard-boiled style.