He plays Matt Sullivan, a single twenty-something web designer who has just suffered a devastating break-up with dream girl Nicole (Shaw).

Ever since the love of his life dumped him, he's embarked on a series of sexually gratifying but emotionally empty one-night stands. When even the sex doesn't strike him as being particularly gratifying any more, Matt finds himself staring into a "deep, black hole".

The solution comes (unwittingly) from his Catholic seminarian brother, and Matt hits upon the cure that he won't have sex for Lent. That means that for 40 days and nights there'll be no touching, no kissing, no foreplay, no fooling around, no self-gratification. No nothing.

Welcoming this opportunity for spiritual purity with no curvy distractions, Matt becomes one of a few select band of people who've given thanks to Jesus Christ as "dude".

To begin with, Matt rises above temptation but then clicks with Erica (Sosammon), who works as a cyber-nanny on the net, blocking off naughty websites. A day spent travelling around San Francisco by public transport delivers the most fun the two of them have ever had... on a bus.

Then it all goes belly-up when she learns about his abstinence - because his workmates have set up an internet spread-bet game based on how long he'll last. With Erica off limits, Matt's imagination runs riot and even his parents can't refrain from rubbing it in over dinner. "Walter, how could you forget the Maui Hilton?" demands his mother of his proud dad.

As the 40-day deadline gets closer, Matt's mind becomes a peep show of tantalisingly unavailable bare flesh - but can he hang on (so to speak)?

Hartnett is an averagely competent comedy lead - pretty much to romantic humour what Keanu Reeves is to action thrillers. But it cannot make its mind up whether it wants to be a simple rom-com or cross the barriers of taste in a Farrelly brothers vein (cue self-abuse in a toilet cubicle gag).

So what you end up with is a movie with a split personality... and you wouldn't particularly want to go out on a date with any of them.

Tim Evans