I’ve read most of George Pelecanos’ 17 previous novels, always with admiration, but four can be singled out as his finest work: “Right as Rain” (2001), “Hell to Pay” (2002), “Soul Circus” (2003) and “Hard Revolution” (2004). All feature a decent and thoughtful – but far from perfect – black man named Derek Strange and are set in Washington. The first three show Strange as a middle-aged private detective. “Hard Revolution” goes back to 1968, when he was a young D.C. policeman; it climaxes with a powerful portrayal of the riots that followed the assassination of Martin Luther King Jr.

Having completed this great quartet, Pelecanos moved on to other characters, but now, in “What It Was,” he returns to Strange, in 1972, as a 26-year-old private detective. The idea for the novel came to him when he was researching a possible Watergate book. He chanced upon a story in The Washington Post titled “Cadillac Smith’s Legend of Violence,” about Raymond “Cadillac” Smith, a notorious criminal of that era. The fictional central figure in this novel, Robert Lee “Red” Jones, is loosely based on Smith’s career.

Jones grew up in poverty and turned to crime. By the time we meet him, he has served a prison term and is an armed killer and brothel owner. He suspects that he won’t live much longer and is determined to “leave behind a name that would be remembered.”

Without romanticizing Jones, Pelecanos gives him his due as a fearless man. Jones’ girlfriend, Coco, runs the brothel he owns. The lovers are presented as a black Bonnie and Clyde. After Red charges into a bar to kill someone, he composes a bit of doggerel about himself that echoes the more ambitious “Ballad of Bonnie and Clyde” that Bonnie Parker wrote 40 years earlier.

Strange is looking for a stolen ring that he thinks Jones has, and his friend, the white detective Frank Vaughn, is seeking Jones for a murder. Once again, they join forces. Vaughn is mildly, unthinkingly racist, but he’s an honest, dedicated cop.

The first Strange novels appeared while Pelecanos was writing for “The Wire,” and they share many of the strengths of that series: specificity, violence, complex characters and unrelenting honesty. It’s typical that, unlike Strange and Vaughn, the novel’s heroes, only the murderer Jones is faithful to the woman he loves.

Many dramas come together in this hard-edged novel. Pelecanos has never been interested in political Washington; his subject is how ordinary people, black and white, survive in a world of poverty, crime and violence. For those who care about the soul music, muscle cars and bizarre clothing of the early 1970s, he recalls them in copious detail.

In recent decades, as American crime fiction has reached new heights, a few novels have been outstanding, including Dennis Lehane’s “Mystic River,” Laura Lippman’s “What the Dead Know” and Michael Connelly’s Harry Bosch series. The Strange novels belong on that list. They’re about crime, but, finally, they’re a profound meditation on good and evil in Washington, mostly in parts of it that are never really seen.