Admit it. Sometimes you talk to yourself. And sometimes, maybe when you are particularly down or stressed, you talk to yourself a lot. And possibly you assume the voice of someone other than yourself. Well, if you accept that premise and are prepared to take it to an extreme, you have the situation portrayed in this serious and intelligent movie.

Mel Gibson plays Walter, a business executive who has spiralled to the depths of alcoholism and depression. Nothing has worked to alleviate his condition; he just wants to sleep. And then, in extremis, he finds his voice. He can communicate. That his new voice is an amiable Cockney worthy of Ray Winstone, and is delivered via a beaver glove puppet, is perfectly natural to him, extremely difficult for his family, and utterly compelling for us.

If you remember a remarkable indie film from a few years back, Lars and the Real Girl, in which Ryan Gosling played a loser and a loner who convincingly re-integrates himself into society via his friendship with a blow-up doll, you are in the same sort of territory. Gibson, without question, deserves great credit for his performance here. Never has he looked so careworn, so desperate, and yet so energised. Jodie Foster, who plays his loyal but exhausted wife, directs the film with a seriousness of purpose called for by Kyle Killen’s uncompromising script, resisting any temptation to trivialise, romanticise or jollify Walter’s difficult journey. The film does, however, spend too much time on the sub-plot concerning Walter’s son Porter (Anton Yelchin) - clearly on the road to being as batty as his father - and his involvement with high-school sweetie Norah (Jennifer Lawrence).

However it is Gibson who carries the day. That the beaver really does come to life on the end of his arm is extraordinary. Mental illness has often proved to be fertile territory when awards are handed out. Mel Gibson for Best Actor? I wouldn’t bet against it. The music is very good as well.