"Gold Shield Blues," by Jeffrey J. Mariotte, in San Diego Noir, Akashic Books, 2011.
The noir city books by Akashic Books are always a mixture of true noir stories and stories that have some but not all elements of the genre. (The best tales can fall into either category, by the way.)
Mr Mariotte has provided a classic noir tale. The narrator, Mike Rogers, is a security guard in the swanky Soledad Mountain neighborhood of San Diego. One night he gets called out to a possible intruder incident and meets a wealthy man with a beautiful young wife. This being noir you can pretty much guess where things will go. But Mariotte has some nice surprises for us (and some unpleasant ones for Rogers, of course.) One thing I like is that he follows the trail of conspiracy to its logical conclusion: how can you trust someone with whom you have shared a betrayal?