What makes Dewey's pulp mysteries so readable and compelling is the hero is, truly a good guy. Compare to the Continental Op, who has no trouble arranging murders, Marlowe, who is too cynical to believe in anything, or Sam Spade, a real POS.  They might have a heart of gold but you really have to dig to get a look at it. Mac, by contrast, is a decent guy - and we know, because he's not the only decent guy in Dewey's world. That means when he steps up to protect someone we feel something about it, and want him to succeed.  Here, Mac is spiralling around a murder, making mistakes, getting tangled deeper and deeper, but ultimately he does it because he sees there's integrity in the world in danger of being brought low. It's a real pleasure.  Dewey is the undiscovered master of American noir.