A lesser book than Double Indemnity, but continuing on the same ideas, namely: how do you commit a perfect murder? In "The Postman", Frank is a not-so-smart petty criminal who has an affair with the wife of his Greek employer. They decide to kill the man and collect the money from his restaurant and the insurance. But there are many holes in their plot and they rapidly run into an increasing amount of trouble.

It is hard to find any sympathetic characters in this book, except for the Greek maybe. But you don't really sympathize with Frank and his mistress. What Cain did well, was telling the story through the eyes of Frank. Mostly the point of view in those 1930's thrillers is an incredibly sharp detective who immediately understands more than the reader and who thinks three steps ahead of everyone else. In this case, Frank is dumber than the reader, you hear him making mistakes, if you were there and were his friend, you'd shout: "Don't do it! You'll only end up in jail, or dead!" It can't be easy for an author to tell a story through a character that doesn't understand what is happening, while the reader must know and see more than the protagonist does. Cain managed to do that very well.