Although Mario Puzo actually wrote about a great many subjects -- gambling, politics, postwar military life, the Italian-American immigrant experience -- a single, lucrative obsession surfaced in his fiction again and again: the history and evolution of the Mafia in 20th-century America. His final novel, the posthumously published Omerta, revisits that obsession and forms the independent third installment in a thematic trilogy that began with The Godfather and continued, in 1995, with The Last Don. In these three novels and in their 1984 sibling, The Sicilian, Puzo created a fictional world with a mythical resonance all its own and invested the realities of organized crime with a lurid, operatic grandeur. Omerta introduces a new Mafia family worthy of the Corleones and the Clericuzios: the family of Don Raymonde Aprile. Their story begins in Sicily in 1967, when the dying Don Vincenzo Zeno -- 'the last of the true Mafia chiefs' -- entrusts the young Raymonde Aprile with the task of raising his soon-to-be-orphaned two-year-old son, Astorre. Following this brief prologue, the novel moves forward nearly 30 years to the world of contemporary New York. Don Raymonde is now retired and has realized one of the great dreams of the career criminal: He has become legitimate. In the grand tradition of the American robber barons, he has extricated himself from all illegal activities, helped his children establish themselves in safe, prestigious professions, and become 'a gentleman banker and pillar of society.' Three years after his retirement, he is shot to death on the steps of St. Patrick's Cathedral by a pair of professional hit men. In the aftermath of the Don's death, Astorre, his adopted son, takes center stage. Astorre, on the surface, is a harmless sort: a wedding singer, horseman, and ladies' man who earns his living by managing the Aprile family's macaroni franchise. He is also a 'Qualified Man,' trained in the ways of the old Mafiosi and steeped in the Sicilian traditions of honor and vengeance. Astorre attempts to follow his late guardian's instructions by protecting the Aprile heirs and by preserving the integrity of their multibillion dollar banking interests. But at the same time, he follows the dictates of the ancient code of Omerta and ruthlessly pursues the men responsible for Don Raymonde's murder.Astorre's quest brings him into contact with a vivid, often vile gallery of supporting characters. Among them are a rival Mafia chieftain with his own undisclosed agenda; a South-American drug lord with a demented desire to own and operate his own nuclear arsenal; an FBI agent whose obsessive dedication leads to tragic consequences; two lethal, deeply compromised NYPD homicide detectives; and a pair of charming, athletic fraternal twins who specialize in murder for hire. Astorre's encounters with these and other, violent and corrupt players nearly cost him his life and culminate in a bloody confrontation in which justice -- Sicilian style -- prevails. Omerta is a spare, tightly plotted novel that encapsulates the changing nature of the Cosa Nostra in little more than 300 pages, moving from the hill towns of Sicily -- where patriarchal chieftains rule with Biblical authority -- to the boardrooms of Manhattan, where modern bandits wear three-piece suits and theorize about 'synergy' and 'global syndication.' Omerta may not be Puzo's masterpiece -- it's slightly less involving than its predecessors, and a number of passages have an underdeveloped, slightly unfinished quality -- and it's unlikely to eclipse the popularity of The Godfather. Still, it's a gripping book by a gifted writer who was both a craftsman and a storyteller and who opened up a corner of the world that no other novelist saw as clearly, or wrote about as well.