Gus Murphy, the hero of Reed Farrel Coleman’s gracefully gritty novel “What You Break,” is a troubled man. He has struggled with grief and rage since the death of his 20-year-old son. In its painful aftermath, he and his wife divorced. He has retired from the Suffolk County, Long Island, police force and now works for a second-rate hotel where he drives a shuttle bus and doubles as house detective.

The author Reed Farrel Coleman (Adam Martin)

Coleman, who has published more than 20 novels and won major crime-fiction prizes, writes skillfully about weapons, car chases, police work and his hero’s many brawls. He also wants us to know that for most people in Long Island, the fashionable Hamptons might as well be on Mars. His Long Island is scruffy, blue-collar, corrupt, choked by traffic and fueled by fast food, cheap beer and unrelenting anger. Jay Gatsby isn’t in the picture.

In this, the follow-up to his acclaimed 2016 novel “Where It Hurts,” Murphy is soon caught up in two dangerous investigations. In one, ex-priest Bill Kilkenny, who has helped Murphy deal with his grief, introduces him to a rich, obnoxious man who wants the ex-cop to investigate the murder of his granddaughter. A reluctant Murphy accepts the assignment after the man offers to start a foundation in honor of Murphy’s son.

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The other challenge arises from his friendship with a Russian named Slava who also works in the hotel and once saved Murphy’s life. We learn that, back in Russia, Slava was involved in a politically motivated bombing that killed many innocent people. Now a formidable Russian assassin has come to the United States to kill Slava. Murphy vows to protect his friend, even if what he did was wrong. The stakes rise when the assassin threatens harm to Murphy’s girlfriend unless he reveals where Slava is hiding.

Violence permeates the novel. Kilkenny, the ex-priest, left the church because, when he was a chaplain in Vietnam, he had to kill a teenage girl who was throwing grenades into a field hospital. A larger Vietnam atrocity, one that recalls the 1968 My Lai Massacre, also figures in the plot, as do a vicious teenage gang and people who manufacture untraceable “ghost guns” that are prized by drug cartels and terrorists.

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“What You Break,” by Reed Farrel Coleman (Putnam)

The book is also punctuated with pithy and vivid asides. Murphy reflects: “We all come into the world in pretty much the same way, yet there are many, many ways to leave it. And leave it we will, inevitably and alone.” He tells of a man who insists prayers are answered: “He said God answered them all the time, but that his answer was mostly no.”

Amid such soulfulness, it’s jarring to find so many passages bragging about Murphy’s intimate life. One morning, his ex-wife drops by to discuss her marriage to another man and the two soon wind up in bed. When Murphy interviews an attractive, somewhat older woman, she abruptly declares that “if I was about twenty years younger, there’s no way you’d be leaving here without bedding me.” She restrains herself but in parting, she kisses him “square on the mouth.” Upon reflection, he decides that the woman wasn’t interested in sex, that indeed he finds desperation and darkness in her kiss. Whatever happened to gratitude?

All this is harmless enough, but the book is sufficiently impressive that you wish the author had toned down Murphy’s role as Casanova. Coleman is a talented writer, whether or not the women of Long Island find his battered, fearless hero irresistible.

Patrick Anderson regularly reviews mysteries and thrillers for The Washington Post.