Written in 2023 by acclaimed mystery and crime author Dennis Lehane, Small Mercies is set in South Boston and outlines the many struggles of Mary Pat Fennessy as she searches for her missing daughter in a city rocked by two of the darkest periods in Boston history: the 1974 busing riots and the murderous reign of crime boss James “Whitey” Bulger. Lehane originally made his reputation with contemporary crime thrillers such as Gone Baby Gone (1998) and Mystic River (2001), but his more recent novels have explored the history of South Boston, including The Given Day (2008), which highlights the infamous 1919 police strike in Boston, and Live by Night (2012), which takes place during Prohibition.

Whereas Lehane’s other historical novels focus on multiple generations of the fictional Coughlin family, Small Mercies is a stand-alone novel that sheds a penetrating light onto many contemporary issues, such as racial discrimination and violence, incidents of police violence, and the widespread effects of organized crime. Boston had to revisit Bulger’s crimes when he was arrested in 2011 after a long disappearance, and his former associates and victims appeared as witnesses or observers at his 2013 trial. High-profile incidents of police violence across the country also forced many cities, including Boston, to confront their own legacies of racial discrimination, and thus, the plot of Small Mercies is relevant to many ongoing social issues. Apple TV is currently developing the book into a miniseries.

This summary is based on the first hardcover edition published by HarperCollins (New York: 2023).

Content Warning: Both the novel and this guide contain depictions of racism, racial discrimination, drug abuse and addiction, violence (including the unrealized prospect of a school shooting), and statutory rape.

Plot Summary

Small Mercies is the story of Mary Pat Fennessy, a single mother eking out a hardscrabble existence as a caretaker at a Catholic nursing home in 1974 South Boston. The summer heat is punishing, and tensions are high due to a recent federal court order to desegregate schools by busing students from majority-Black or white neighborhoods to one another’s schools. Mary Pat has suffered grievously—her first husband disappeared in a likely gangland murder, her second husband left her, and her son died of a heroin overdose. She sees the controversy around desegregation and busing as just one more difficulty that she and her 17-year-old daughter Julia must navigate. One day, Julia (whom everyone calls Jules) does not return home after a night with friends, and that same morning, Mary Pat sees a news story about a young Black man named Augustus “Auggie” Williamson who died in the Columbia subway station in Dorchester: a majority-white area. She quickly deduces that he is the son of her coworker, whom she knows as “Dreamy.” As more time elapses and Jules does not resurface, Mary Pat undertakes more aggressive measures to find her daughter, including beating up her boyfriend at a bar owned by local crime lord Marty Butler. She is soon visited by Detective Michael “Bobby” Coyne, who tells her that eyewitness testimony implicates Julia in Auggie’s death. Mary Pat also discovers that Jules was having an affair with one of Marty Butler’s top hitmen, Frank Toomey. Armed with that knowledge, she asks one of Butler’s lieutenants, Brian Shea, to find out what happened to Jules, but shortly afterward, she receives a visit from the boss himself, who offers her a package of money to go to Florida and forget the whole thing. With that, Mary Pat realizes that Jules must be dead.

Mary Pat decides to find out the truth about Jules’s likely murder in order to exact vengeance on those responsible. After kidnapping and torturing Jules’s boyfriend, she learns that Jules had become pregnant and was demanding financial support from Frank. Overhearing the conversation and distressed by Frank’s refusal to help Jules, Auggie Williamson solicitously asked if she was all right. She and her companions, whose racism caused them to be outraged by Auggie’s presence, chased Auggie into the subway station and threw beer bottles at him until he knocked himself unconscious against the side of a train. As they fled from the station, Frank emerged to demand that they kill Auggie. After Jules delivered the killing blow with a brick in order to prevent her companions from inflicting an even more painful death on Auggie, she got into Frank’s car. Perceiving her method of killing Auggie to be “merciful” and therefore “weak,” Frank took her back to Butler’s house and stabbed her in the heart.

Mary Pat’s next step is to find George Dunbar, a local drug dealer from whom her son used to purchase heroin. She discovers that George is selling weapons to Black activists and drug dealers in Mattapan. She later ambushes him and forces him to take a dose supply of his own heroin, at which point he confesses that Jules’s body is buried beneath the concrete of Butler’s home. Mary Pat then sets Butler’s house on fire so that the police will find the body. The police also learn from George that the Butler organization was selling weapons to Black drug dealers in the expectation that they would attack South Boston High and thereby undermine the busing initiative at its inception.

Mary Pat then goes to an anti-busing rally to find Frank Toomey, and after a long period of surveillance, attacks him in his driveway, kidnaps him, and drives him to the fort at Castle Island. Soon surrounded by Butler’s men, she executes Frank and shoots Brian Shea, who is then killed in an exchange of gunfire. Mary Pat is shot by Butler and dies while trying to return fire. After the fact, it is discovered that Detective Bobby Coyne will most likely be unable to bring charges against Butler for Jules’s death or Mary Pat’s death. Before Mary Pat’s death, she used the money that Marty Butler gave her to provide Jules with a mausoleum regularly stocked with fresh flowers.