Set against the social upheaval following World War I, the novel interweaves three men's lives across a landscape of racial violence, labor unrest, and political corruption, culminating in the 1919 Boston Police Strike.
The novel opens in September 1918 with Babe Ruth, the young Red Sox slugger, stumbling off a train in rural Ohio and joining a pickup baseball game among Black men. He watches Luther Laurence, a former semipro player, steal home in a breathtaking display of speed. When white major leaguers drift over and take control, disputed calls go in their favor every time. Asked to settle a close play, Ruth lies and sides with the white players. The Black players walk off the field without a word, and Ruth returns to the train haunted by shame.
In Boston, Danny Coughlin is a police officer and eldest son of Captain Thomas Coughlin, a shrewd political operator who wields backroom power in the city's Irish ward system alongside his best friend, Lieutenant Eddie McKenna. A survivor of a 1916 anarchist bombing at his station house, Danny has recently ended a secret affair with Nora O'Shea, an Irish immigrant who works as a domestic in his parents' home. His father and other power brokers recruit Danny to infiltrate the Boston Social Club (BSC), the policemen's fraternal organization that serves as an informal union, and to go undercover in radical Bolshevik groups. In exchange, they promise him a detective's gold shield. When Danny's brother Connor Coughlin announces plans to marry Nora, the personal and political threads of Danny's life tangle irreparably.
Luther Laurence loses his factory job in Columbus, Ohio, as employers prepare to rehire returning white soldiers. His pregnant girlfriend, Lila Waters, persuades him to move to Greenwood, the prosperous Black neighborhood in Tulsa, Oklahoma. Luther takes a job at the Hotel Tulsa and begins running numbers for Deacon Skinner Broscious, a gangster who controls Greenwood's underworld. His closest friend, Jessie Tell, who has a heroin addiction, has been skimming from the Deacon. When the Deacon discovers the theft, he holds both men responsible and forces them to collect debts from flu-stricken families at gunpoint. The errand ends in catastrophe: Jessie opens fire at the Deacon's club, and the Deacon's enforcer Smoke kills Jessie. Luther shoots Smoke and executes the Deacon, then rushes home. Lila refuses to flee. Luther leaves money under the mattress and drives into the night.
The influenza pandemic ravages Boston. Danny works tirelessly in the tenements, carrying out the dead. His patrol partner Steve Coyle contracts influenza and survives but is permanently unable to return to duty. Luther flees across the country. In East St. Louis, his Uncle Hollis tells him his father was murdered in the 1917 race massacre and that Smoke survived with a bounty on Luther's head. Hollis sends Luther to Boston, where Isaiah Giddreaux, head of the local National Association for the Advancement of Colored People (NAACP) chapter, takes him in, secures him a houseman's job with the Coughlin family, and puts him to work renovating a building on Shawmut Avenue for the NAACP's new headquarters.
Danny, living under an alias, infiltrates a Latvian immigrant Bolshevik group while attending BSC meetings. He begins an affair with his neighbor Tessa Abruzze, only to discover she is actually Tessa Ficara, wife of the Galleanist bomb-maker Federico Ficara. Galleanists are followers of Luigi Galleani, an anarchist who advocated violent revolution. Danny finds himself genuinely drawn to the policemen's cause and tells his father he refuses to inform on his fellow officers.
On Christmas night 1918, Quentin Finn appears at the Coughlin home and claims Nora as his wife. Nora admits the marriage but reveals Quentin purchased her when she was 13. Danny beats Quentin in the street and confronts his father, suspecting Thomas engineered the exposure to sever both sons' attachment to Nora. Thomas orders Nora out, and the family fractures. That same night, Commissioner Stephen O'Meara dies of a cerebral hemorrhage, removing the policemen's strongest ally. His replacement, Edwin Upton Curtis, despises organized labor. After Danny's cover with the Bolsheviks is blown, he returns to the BSC full time. In January 1919, a molasses tank explosion devastates Boston's North End. When Federico targets a church with a dynamite-laden car, Danny shoots and kills him, saving the parishioners. Tessa escapes with a wound.
Luther and Danny form an unlikely alliance: Luther will report on Nora's situation with Connor, and Danny will try to shield Luther from McKenna. Luther develops a friendship with Nora and works alongside Clayton Tomes, a fellow houseman, renovating the NAACP building. McKenna, however, discovers Luther's Tulsa past and threatens to have Lila arrested and their baby seized unless Luther steals the NAACP mailing list and builds a hidden vault in the building. When Luther resists, McKenna shoots and kills Clayton to demonstrate his power, then forces Luther to bury the body and store a toolbox of guns in the vault.
On May Day 1919, police violently suppress an illegal march. That night, Luther finds Danny badly beaten and carries him to a clinic, saving his life. Danny and Nora reconcile and marry. Luther removes the planted guns from the vault and places the toolbox on McKenna's roof. McKenna, drinking alone, bends to inspect a loose gutter and falls to his death. Thomas kneels by his oldest friend's body and accepts the finding of accidental death.
The BSC votes to accept an American Federation of Labor (AFL) charter, with Danny as vice president. Curtis suspends 19 union officers. Civic leader James Jackson Storrow brokers a compromise: The city will meet the men's demands if they relinquish their AFL affiliation. Danny sells the deal by a narrow vote, but Curtis ignores the compromise and fires all 19 officers. The union votes to strike. On September 9, 1919, Danny leads the walkout. The city erupts into two nights of rioting. Governor Calvin Coolidge initially refuses to call out the State Guard. Thomas leads a force through South Boston, clearing the streets. On the second night, Mayor Andrew Peters activates the Guard. In the chaos, Connor rescues Danny's younger brother Joe Coughlin from the mob but is permanently blinded when glass from a shattered car window strikes his face. Danny's family blames him.
Curtis fires all strikers and hires replacements at the higher wages the men had demanded. Coolidge's declaration that there is no right to strike against public safety makes him a national hero. Newspaper stories reveal Danny's prior involvement with the Ficaras, destroying public sympathy for the strikers. During the riots, Luther survives an assassination attempt by a man Smoke sent from Tulsa, which hardens his resolve to return home. Danny's former partner Steve Coyle tracks down Tessa Ficara, and she shoots him. Danny pursues and kills Tessa but is shot three times by another Galleanist. Luther kills the shooter with a brick hurled from below, saving Danny's life a second time. Danny nearly dies from his wounds but gradually heals with Nora at his bedside.
Danny meets his father one last time on a snowy night and tells him they are leaving. Thomas promises to write if Danny writes, and they walk away in opposite directions. Luther returns to Tulsa in disguise and confronts Smoke at gunpoint. Rather than kill him, Luther offers $2,000 and proposes a truce: He will stay out of Greenwood nightlife if Smoke lets him live in peace. Smoke accepts. Luther walks to his house and finds Lila hanging laundry with baby Desmond at her feet. She whispers his name and holds out her hand. Luther drops to his knees and weeps.
In January 1920, Ruth rides a train to New York, newly traded to the Yankees. He strikes up a conversation with a big ex-copper and his Irish wife heading west to start over. Ruth envies the bond between Danny and Nora, a peace he fears he will never know, and climbs into the car the Yankees sent, telling himself it will be a good decade.