In the 1940s, Patricia Highsmith graduated from Barnard, lived in Greenwich Village (it was cheap and bohemian then), and wrote scripts for comic books. Her first novel, Strangers on a Train, was published in 1950.
Alfred Hitchcock bought the rights, and the film version premiered in 1951. Thanks to its success, Highsmith was a household name at age 30. She wrote 21 more novels and many short stories and lived well off her writing.
She wasn't just lucky. She had a truly great idea. To paraphrase, "You murder my enemy, and I'll murder yours." These are to be the perfect crimes, because the murderer has no motive, and the person with a motive has an alibi.
Strangers on a Train has more than a great idea. The execution is brilliant. We get to know the two men who would do such a thing. We come to believe that such people would enter into such an evil conspiracy.
Hitchcock's film version makes critical changes in the plot so we have a sympathetic character to root for. It's still a great film. Reading the book is a different, great experience.