The Savages (15)

The truthful picture of the American family is not The Waltons, or The Simpsons, but it might be a lot like The Savages, Tamara Jenkins's tragicomedy about old age, sickness and death. With that combination you're hooked already, yes? Give it a chance, though, because it's a rare movie that can land a punch in the gut one minute and rouse a belly-laugh the next.

It also brings together two of the most compelling screen actors of the current decade. Laura Linney plays New York temp Wendy Savage, a brittle and insecure thirtysomething who's still trying to make it as a playwright, and still fooling around with a married man (she seems to prefer his Labrador to him). Philip Seymour Hoffman plays her brother Jon, a glum professor of drama in upstate NY who's trying to finish his study of Brecht ("I know everyone's really itching for a book about Bertolt Brecht this holiday season").

Their lives start to change when news comes from Arizona that their enfeebled dad (Philip Bosco) has become difficult – a "toiletting incident" kicks off proceedings – and needs family assistance. Suddenly his children find themselves obliged to deal with dementia head-on. "Does it smell?" Wendy asks Jon about the care home he's found. "They all smell," he replies.

Listening to the sharp-witted parry and thrust of Jenkins's screenplay reminds me how much I enjoyed her first movie, Slums of Beverly Hills, all of 10 years ago. It is searingly honest, for example, about the bloody nuisance of having to look after an ill parent, specifically one who has not earned his children's love. "Maybe Dad didn't abandon us," muses Wendy, "he just forgot who we were."

That brother and sister are both romantically unfulfilled and mildly addicted to painkillers tells its own story, and Jon's attempt to palm off responsibility on Wendy raises the pale ghost of sibling rivalry. "Your life's more portable than mine," he tells her. "What do you mean by that – like a toilet?" Jenkins gets all the little details right, too, such as the titles of each sibling's work-in-progress: Wendy's semi-autobiographical play about her childhood is called Wake Me Up When It's Over, while Jon's Brecht book is entitled No Laughing Matter. We can assume it won't be on Oprah's book club.

The pinched horizons of the Savage family might have been a depressing experience but for Jenkins's humane tone of consolation and the superb playing of Linney and Hoffman. The scene in which Jon and Wendy leave their father in the care home the first night and walk out into the car park accurately distils what any child might feel on "abandoning" a parent – an internal commotion of guilt, relief and misery. "We're just horrible people," cries Wendy, uselessly.

Linney has played a variation on this character before in You Can Count On Me (she was involved with a married man then, too), and yet no matter how shrill her indignation or pernickety her manner she always finds a core of human vulnerability to keep us rooting for her. You may already be tired of hearing how great Seymour Hoffman is; suffice to say that this is as good as his older-brother role in Before the Devil Knows You're Dead and better than his turn in Charlie Wilson's War, for which he's been Oscar-nominated. Linney and Jenkins have also been nominated for Best Actress and Best Original Screenplay – let's hope justice is done.