Small-time hood Alfredo Martelli (Marcello Mastroianni) traffics in antiques, stolen art and occasionally women. He's arrested not for these crimes, but for allegedly murdering his rich mistress Adalgisa (Micheline Presle), who in fact was killed by another man. Martelli seeks to prove his innocence to Inspector Palumbo (Salvo Randone), but in doing so he can only implicate himself in other crimes. Will Alfredo learn from his experience, or continue on his lifestyle as before?
With moody film noir-style photography, fractured flashbacks and Pierro Piccioni's mellow jazz score, The Assassin starts out in the vein of Hitchcock or another procedural. We soon realize that Alfredo didn't kill Adalgisa, who in fact encouraged his dalliance with a younger woman (Cristina Gaiolini), with neither motive nor evidence pointing towards him. Hollywood convention encourages us to wait until Alfredo clears his name, yet Petri shows little interest in that side of the story. Rather, he treats the affair as a karmic comeuppance for someone who's spent his life skirting the law and only now is being brought to account.
While The Assassin lacks the political edge of Petri's later work, its darkly humorous structure retains a kick. Slowly, Palumbo's investigation, and Alfredo's own guilt-ridden flashbacks, reveal his criminal past. We can laugh at his proclaiming himself as a "self-made man" over minor swindles, but then we meet a family whose business he ruined, a waitress he trapped into prostitution, assorted other victims of crimes large and petty. By the film's end, Petri offers little support for Alfredo beyond his innocence in a specific crime, and only then if he's willing to recant his earlier lifestyle. Evidence suggests, however, that's not in the card.
Marcello Mastroianni dominates the movie, emphasizing Alfredo's self-pitying indignation and moral quandaries. It's to Mastroianni's credit that Alfredo retains sympathy through most of the movie; the movie's clever set-up allows us to hope he's innocent, even as his true colors shine through. It's a slick acting job, with Mastroianni making his character extremely human, aware of his shortcomings but unclear on how to act on them. He's less tragic than pitiable, yet by film's end even that strand wears thin. There's a functional supporting cast, with Micheline Presle's perpetually amused victim and Andrea Checchi's goonish villain making impact, but it's all Marcello's show.
Perhaps it's best that Petri, in this early outing, doesn't inflate Alfredo's misdeeds into an allegory of societal rot. It's a sad, dirty tale of a criminal who knows he's doing wrong, feels bad about it, yet does it anyway because it's the easiest way out. Remarkably free of sentimentality or moralizing, The Assassin remains an engaging experience.