Pierfrancesco Favino plays Mafia informant Tommaso Buscetta in the true-crime flick “The Traitor.” (Sony Pictures Classics)

Rating: (3 stars)

Based on the life of Tommaso Buscetta, the Italian mafioso-turned-informant whose testimony in high-profile trials in the 1980s and 1990s helped shed light on the inner workings of La Cosa Nostra and bring several of its members to justice, “The Traitor” is as just as brutal as you might expect from such a true-crime tale. Yet 80-year-old director Marco Bellocchio (“Good Morning, Night”) enriches the on-screen bloodshed with richly detailed performances and an unpredictable energy that lifts the period crime drama above a mere gangster flick.

The film’s shifting timeline begins in 1980 at a Palermo estate where generations of Italian families have gathered before. The gathering we are witnessing is an attempt to make peace between warring factions of the mafia, although it looks like a celebration, complete with fireworks. Too quickly, however, the festive tone deteriorates into what is effectively a story of familial betrayal.

Pierfrancesco Favino (“The Chronicles of Narnia: Prince Caspian”) stars as Buscetta, a “made man” (or fully initiated member of the mafia) who gets caught in the middle of the vicious heroin wars that bloodied Palermo streets in the 1980s. A “man of honor,” as he calls himself, Buscetta also had earned another nickname: “boss of two worlds,” based on his criminal enterprises in Sicily and Brazil, where he fled Italian authorities. When the Sicilian drug trade heats up, Buscetta’s eldest sons are killed by a rival clan, as if daring him to return home. And after making a deal with Brazilian officials, it’s in Italy that Buscetta earns the film’s titular nickname, laying bare the mafia’s power structure to the authorities, and fingering his former colleagues for Judge Giovanni Falcone (Fausto Russo Alesi).

Pierfrancesco Favino as plays mafia informant Tommaso Buscetta in “The Traitor.” (Lia Pasqualino/Sony Pictures Classics)

Even with on-screen titles that identify who’s who, it can be hard to keep track of the complex mob alliances in this story. But Bellocchio has a trick up his sleeve that builds tension as the bodies pile: When somebody’s about to get killed, an on-screen counter appears with a running tally of the fatalities so far. Yes, it’s a gimmick, but it makes plain how many lives were wasted during this tumultuous era.

For all the carnage, the film is even more volatile in courtroom scenes in which Buscetta confronts such fellow criminals as Pippo Calò (Fabrizio Ferracane). (Calò seems like an avuncular fellow — until we learn how many people he’s killed.) During the trial, shouting matches turn the Italian justice system into what looks like a circus, all the more so since the members of the Sicilian mafia are kept in cage-like pens in the back of the courtroom.

This setup leads to a juxtaposition that conveys the same vigor that made Bellocchio’s 1965 debut “Fists in the Pocket” such a wild ride: When Buscetta faces the iron bars that separate him from Calò, the film flashes back to a scene from some 20 years earlier, during which Buscetta, while at the zoo with his family, watches a white tiger pace in its cage. The bestial metaphor is a heavy-handed one, but it comes so out of left field that it hints at a feral mentality on the director’s part as well. If “The Traitor” proves anything, it’s that an 80-year-old filmmaker can still pounce.

R. At area theaters. Contains violence, sexual material, coarse language and brief graphic nudity. In Italian with subtitles. 150 minutes.