Matt Sullivan (Hartnett) is young, single and fucked up. He's still carrying a torch for Nicole, his ex of six months' standing. The harder he parties, the worse it gets. And so it is that Matt resolves to abstain from sex for Lent: 40 days and nights. Okay, so it's probably more difficult for Hartnett than the rest of us (and, admittedly, his vow of chastity extends to self-love, which raises the stakes), but whatever its dubious merits as a barometer of contemporary sexual mores, it's a dopey premise for a movie. Naturally, our boy has no sooner forsworn carnal pleasure than he falls in love - Sossamon making the most of very little - while his dot.com colleagues post bets on how long he stays the course. You might think you know how this story has to climax, but you would be wrong: it's more sentimental than that. Playing earnestly straight, Hartnett's such a thoroughly responsible presence it's impossible to believe he would get himself into such a mess. Between them, director and star steer the movie away from fratboy farce towards the conventional pieties of the traditional romantic comedy. The result is tastefully crass, fitfully amusing and instantly forgettable.