Pelecanos's books are just my kind of reading - a mystery/police procedural that digs into the dark heart of human nature.
Gus Ramone is a Washington DC homicide detective and former Internal Affairs investigator, 20 years on the job, married to a woman he still loves (and who still loves him), trying to do right by his two children. Not an alcoholic, divorced, or emotionally shut-down -- despite the horrible things he has seen over the years, he has managed not to become bitter and jaded, and he tries always to do his job by the book.
Contrast this with Dan "Doc" Holliday, who was at one time Ramone's partner, until he quit the force in the face of a threatened IA investigation, and now has a small limousine business, mostly transporting wealthy businessmen and athletes to and from the airport and around the city. Doc is a heavy drinker and spends a lot of time picking up women in bars for casual sex. He resents having been (as he sees it) forced out of police work.
When the body of a young man is found in one of the city's community gardens, dead from a gunshot wound, both Ramone and Holliday independently note strong similarities to a series of murders that happened 20 years before, when both of them were rookies. Holliday's investigative instincts are reignited, and he contacts T.C. Cook, the legendary detective who worked on those cases and never really gave up the hunt, even after he retired. Both men feel they have something to prove: Holliday that he really was "good police", despite his fast and loose attitude toward police work, and Cook because the case remains open and still haunts him.
Ramone's by-the-book nature requires that he not encourage two civilians' independent investigation, but his sense of responsibility for the IA case that took down Holliday and his respect for Cook prompt him to ally himself with them to determine what happened to Asa Johnson, and whether the Night Gardener is indeed at work again.
Portrays police detectives and officers as individuals balancing the usual work/family conflicts, workplace politics, etc., rather than assigning the various characters stereotypical "roles." Ultimately it's less about the case than about the people.