"I, so far as I can sense the pattern of my mind, write of the wish that comes true, for some reason a terrifying concept, at least to my imagination. . . . I think my stories have some quality of the opening of a forbidden box, and that it is this, rather than violence, sex, or any of the things usually cited by way of explanation, that gives them the drive so often noted." James M. Cain offered this explanation of his writing in the preface to The Butterfly in 1947, when his most important fiction was behind him. With publication of his first novel, The Postman Always Rings Twice, in 1934 Cain immediately became a best-selling author, and critics at once pigeonholed him in the hard-boiled school. In 1941 Edmund Wilson identified Cain as the best of "the poets of the tabloid murder" in his seminal work on the California novelists of...