A witty, tragic tale of possible murder

Paul Giamatti plays a flawed but forgivable man who might have murdered his friend in <em>Barney’s V

For an actor, your face is your destiny. So it's no surprise that Paul Giamatti has made a career out of playing flawed but forgivable men. He just looks put-upon – two parts naughty schoolboy to one part unkempt software billionaire, with just a dash of sulky artist.

His air of harried sweetness serves him well in his new film, Barney's Version, a rambling picaresque based on the 1997 novel by the Canadian author Mordecai Richler. Barney Panofsky is not, at first glance, a sympathetic character: he neglects his first wife, loathes his second and skips out of their lavish wedding to chase his third. He drinks too much, smokes endless cigars and tries not to talk about sex with his father (played with obvious relish by Dustin Hoffman). Oh, and it's also possible he murdered his best friend. The film travels back through his memories, implicitly asking whether we can trust his "version" of events.

To be honest, it's unlikely that I would have seen Barney's Version if I hadn't been interviewing Rosamund Pike – who plays the third Mrs Panofsky – for the NS. But I'm certainly glad I did, because it's witty, tragic and moving: Pike and Giamatti create a long-standing relationship that feels warm and authentic. (If there's one thing that gets me teary when reading a book or watching a film, it's a well-judged portrayal of love that lasts a lifetime. You should have seen me during Up.)

Yes, Barney's Version has all the problems you'd associate with a book adaptation – it's about 20 minutes too long, for a start (I'd have been tempted to ditch the first wife). Then there's Barney's descent into Alzheimer's, which provides the framing device for the film's reminiscences of the past. In the book – which I confess I haven't read, although I want to – I imagine this is a more gradual process. In the condensed medium of film, however, Barney jumps pretty much straight from forgetting where he's parked his car to sitting blankly on a bench, completely gone, which robs the decline of much of its pathos.

Also, I feel bad that I still don't know the answer to the central question posed by the film – should we trust Barney's memory of the day his best friend died? There was what was clearly supposed to be a revelatory scene at the end of the film but I wouldn't like to say definitively what it was supposed to mean. (Any help on this front greatly appreciated, though you should probably put a huge great SPOILER tag on the comments.)

Still, it's always easier to articulate what you don't like about a film rather than what you do. There's plenty of great stuff in Barney's Version. Dustin Hoffman having a whale of a time, for a start, and giving his son pep talks along the lines of: "You're married to a woman who has a beautiful rack!"

All the actresses playing the wives earn their keep, too. Minnie Driver has the flashiest part, unleashing her inner neurotic as the second Mrs P, but Rosamund Pike brings much-needed dignity to her role as the spunky-but-saintly Miriam. In the end, you feel that Barney must be a decent person because he was loved by her.

Barney's Version is released on 28 January. My interview with Rosamund Pike will appear in an upcoming issue of the New Statesman.

Helen Lewis is deputy editor of the New Statesman. She has presented BBC Radio 4’s Week in Westminster and is a regular panellist on BBC1’s Sunday Politics.