[3] The story is narrated in the first person by Frank Chambers, a young drifter who stops at a rural California diner for a meal and ends up working there.

The diner is operated by a beautiful young woman, Cora, and her much older husband, Nick Papadakis, sometimes called "the Greek".

Cora fells Nick with a solid blow, but a sudden power outage and the appearance of a policeman make the scheme fail.

The lawyer uses the time to manipulate the insurance companies financially interested in the trial to have their private detective recant his testimony, which was the final remaining weapon in the prosecution's arsenal.

After failing as a scriptwriter for Paramount and Columbia studios in 1932, Cain resumed his efforts to write a longer work of fiction.

His short story "The Baby in the Icebox" had impressed Alfred A. Knopf publishers, and with their encouragement and that of playwright Vincent Lawrence, Cain began to write a novel in March 1933.

Walter Lippmann, who Cain had served under as a journalist at the New York World, interceded on his behalf and convinced Alfred Knopf to acquire the story.

Cain and Lawrence insisted that the metaphor of a mail carrier as the agent of fate was essential and prevailed in the title dispute.

[11] The novel elicited high praise from literary critics in the US and abroad, and proved to be a perennial best-seller: "When the book appeared it caused a sensation.

[14][15] Biographer David Madden notes that the opening passages showcase Cain's narrative skill: "The compression, the swift execution of the basic situation [in the first pages] are typical of the entire novel.

Biographer Paul Skenazy noted that the Postman suffered from "simplistic psychological portraits, some mannered writing [and] inconsistencies in the time frame and plot structures...".

[17] Critic Walter Wells in his analysis of Hollywood fiction argued that the "Postman remains a forced, structurally imperfect work [pandering] shamelessly to subliterary taste.

[27]Cain discovered the dramatic component he required for the story in the details of the 1927 Ruth Snyder-Judd Gray case, in which a wife murdered her husband in collusion with her lover, the prototypes for his characters Cora Papadakis and Frank Chambers in Postman.

Biographer Paul Skenazy suggests that Cain was intrigued not only by their adultery and murder, but the subsequent betrayals that sent Snyder and Gray into "a self-destructive spiral.

William Marling, for instance, suggested that Cain may have taken the title from the sensational 1927 case of Ruth Snyder, who, like Cora in Postman, had conspired with her lover to murder her husband.

Cain used the Snyder case as an inspiration for his 1943 novel Double Indemnity;[31] Marling believed it was also a model for the plot and the title of Postman.

[33] In the preface to Double Indemnity, Cain wrote that the title of The Postman Always Rings Twice came from a discussion he had with the screenwriter Vincent Lawrence.

However, the postman rang again and this time the ring was heard; Frank is wrongly convicted of having murdered Cora and then sentenced to die.