The Blue Sweetheart — David Goodis

Thick sticky heat came gushing from the Indian Ocean, closed in on Ceylon, and it seemed to Clayton that he was the sole target. He sat at the bar of a joint called Kroner's on the Colombo waterfront, and tried vainly to cool himself with gin and ice. It was Saturday night and the place was mobbed, and most of them needed baths. Clayton told himself if he didn't get out soon, he'd suffocate. But he knew he couldn't walk out. If he walked out, he'd be killed.
And for what? A glittering sapphire and a beautiful platinum blonde―and Clayton wanted them both; wanted them badly enough to kill for them. Gritty, exotic noir by the author of Dark Passage.