Three generations' worth of love and obsession are the foundation of this tightly worked novel by the author of the popular Spenser series. Parker (Walking Shadow, p. 427, etc.) tells the century-long story of two families: the Irish Catholic, working-class Sheridans and the wealthy and privileged Boston WASP Winslows. They first meet in a hospital in Dublin in 1920, where Captain Conn Sheridan (of the IRA) is recovering from wounds received in the line of duty and Hadley Winslow, whose older banker husband, Thomas, is in Dublin on business, volunteers. They have an affair and Conn becomes obsessively attached to Hadley. She won't leave Thomas, Conn won't leave her, and, frightened at his persistence, Hadley betrays Conn to the British. Conn escapes from Kilmainham Jail and makes his way to Boston, where he marries, has a child, Gus, and becomes a successful police detective. He never recovers from Hadley's deceit, however, and when her beloved son, Tommy, rapes and murders a 12-year-old girl, Conn makes a deal with her: He will bury the case if she agrees to become his lover. He also blackmails her for money. When Corm dies, he leaves the facts of the case as a legacy to Gus, who continues to blackmail the Winslows. Gus also becomes a cop and has a loveless marriage, like his father's, but he adores his son, Chris, and does everything he can to ensure Chris's future success. Chris seems to be fulfilling his father's dreams -- he becomes a lawyer, and then a professor of criminology at Harvard, and in 1993 is made special prosecutor to investigate a raging Irish gang war. But Chris doesn't realize that what he uncovers during his inquiry may destroy not only the gangs, but Chris's own family, and the family of the only woman he has ever loved -- Grace Winslow. A thrilling game of cops-and-Brahmins. Parker is in fine form.