Thomas Dewey (writing here as Tom Brant) is one of the most underrated American mystery authors - underrated, that is, by everyone except American mystery authors, who regularly name him as an influence and admire his work.  This is one of his lesser works, to be sure, but it has the same questions of ethics and justice that his more prominent works contain. As with all crime stories, our protagonist is put in a bad situation by bad people, and allies himself with them in order to survive, but is only drawn deeper in.  The tension of the book is his inner anguish as he begins to realize that he isn't as ethical as he might have considered himself to be - and certainly not as much as he wants to be.  Nor does it fall into the category of "antihero falls for innocent girl and she exists only to redeem him", which many of the sort written at the time did.  It all wraps up rather neatly in the end, perhaps a little too neatly for the anguish and anxiety our main character suffered.  It gives the impression that maybe it wasn't that hard after all.  Still, you can see Dewey's understanding of action scenes and internal expressions within them throughout.