At a time when British crime fiction exerted a strong influence on American writers, Peter Cheyney was the first British author to show that he was influenced by crime fiction in the United States. His novels about tough G-man Lemmy Caution and private eye Slim Callaghan combined fast action with surprises. A popular mystery writer with no literary pretensions, Cheyney sold more than 1.5 million books in 1944 alone. An examination of his popularity shows that he was versatile in the ways he could entertain his large audience. As he progressed, his writing became more subtle, and in his Dark series near the end of his career, Cheyney produced books that vividly conveyed a picture of the divided world of wartime espionage and its cynicism, violence, and double-crosses.