For decades Marco Bellocchio has been making films dealing with important moments of Italian history, most successfully with Good Morning, Night, his look at the Aldo Moro kidnapping by the Red Brigade, and Vincere, about Mussolini. He’s back in Cannes with a film in competition, this time looking at the maxi Mafia trials of the 1990s, which led to a slew of convictions, in part thanks to the traitor of the title, ex-Cosa Nostra ‘soldier’ turned state witness Tommaso Buscetta.

Buscetta is played by the extremely watchable Pierfrancesco Favino, whose portrayal of this don is both highly credible and somewhat disturbing. The latter is not due to Favino’s performance, which is one of his best, but to the director’s choice to depict Buscetta as a man of honour. Instances of Buscetta’s past are glimpsed throughout the film, but there is little evidence of what this man actually did to make his millions. He’s been imprisoned on countless occasions, stating that he knows all of Italy, ‘the prisons, at least’ and yet neither the man nor the director are keen to divulge more information. Is Bellocchio inviting the audience to see this man as delusional? If so, his message isn’t very clear.

Almost every aspect of Buscetta’s character is an enigma. Other than being a family man (three wives and eight kids), he remains pretty unknowable throughout. One thing is for sure, though: there is little about this man that could be construed as honourable and it is the film’s weakness to make Buscetta in any way sympathetic. But its biggest weakness lies in its depiction of Giovanni Falcone, a judge and state prosecutor who instigated the maxi arrests and trials after years of painstaking and dangerous work. He did much of that work with his colleague Paolo Borsellino and both men were assassinated by the Mafia in the summer of 1992. Bellocchio portrays Falcone and Buscetta’s relationship as a friendship based on respect, but this seems impossible to believe and again might be a reference to Buscetta’s delusional nature. Was Falcone really so accommodating and was there really any love between these men?

Even more egregiously, Borsellino does not even get a mention. He is seen in real footage giving a brief sermon at Falcone’s funeral (the archive footage packing more emotional punch than anything else in the movie), but other than that he is a non-presence in the film. Perhaps he was omitted to provide cinematic balance, but it is a gross misrepresentation of the facts and a disservice to both prosecutors.

Bellocchio has chosen to use a straightforward narrative in this film and it’s easy to understand why: with a reality as far-fetched and dramatic as this who needs experimental cinema? It starts with a religious holiday being celebrated in Palermo and looks like an episode of The Sopranos. The audience is given a list of names – far too many to remember – and as the internecine killings begin, Bellocchio tots up the numbers of the dead on the screen. The action moves from Sicily to Brazil and back as we follow Buscetta to his fabulous Rio home and then back to Sicily to search for his two missing sons.

The courtroom scenes in particular are brilliantly managed. The court was an underground bunker built below a prison in order to the avoid problem of moving the multiple Mafia defendants. Kept caged in small groups, the rogues’ gallery causes chaos throughout the trial with ridiculous requests and acts of outright anarchy. Everything about these men is exaggerated, from their suits to their gestures and their desire for power at any cost. There is a great performance by Luigi Lo Cascio, who was in Bellocchio’s Good Morning, Night, as Buscetta’s cohort Totuccio Contorno. The man can only speak in Sicilian dialect and his inability to speak Italian and thus be understood by the court emphasises Italy’s fractured state and highlights how the problems of Sicily are so easily misunderstood by Italians.

The list of sentences at the end bookends nicely with those figures we saw at the beginning. The film ends with footage of the real Buscetta singing at a party and it states that he died, as he had wanted, in his bed. This was a luxury not afforded to Giovanni Falcone and Paolo Borsellino, the real heroes of this true story, and Bellocchio is remiss in forgetting this.