The Four Stragglers (UNABRIDGED‪)‬

"This thrilling novel teems with intrigue and unforgettable characters. It opens during WWI with a few allied soldiers lost at night behind German lines. One of them shoots at another in the darkness. Members of a criminal gang before the war, the men resume their unlawful activities when peacetime returns. The gang’s leader receives a letter that results in his leaving London for a small island off the Florida Keys. He is “as clever a scoundrel and as miserable, inhuman and unscrupulous a one as ever blasphemed the image in which God made him… He is without conscience, ruthless, a fiend who would do honour to hell itself.""
Frank L. Packard authored many popular novels, several of which were made into movies, including a series in which he originated the idea of a heroic crime fighter with a secret double identity. --Lee Smalley"