Will is thirty-six and acts like a teenager. He reads the right magazines, goes to the right clubs and knows which trainers to wear. He's also discovered a great way to score with women - at single parents' groups, full of available mothers, all waiting for Mr Nice.
That's where he meets Marcus, the oldest twelve-year-old in the world. Marcus is a bit strange: he listens to Mozart, looks after his mum and he's never even owned a pair of trainers. Perhaps if Will can teach Marcus how to be a kid, Marcus will help Will grow up . . .
Based on Nick Hornby's novel, this is the book of the film directed by Chris and Paul Weitz and starring Hugh Grant, Nicholas Hoult, Toni Colette, and Rachel Weisz.