Cast: Bradley Cooper, Ed Helms, Zach Galifianakis, Justin Bartha, Heather Graham.

WHEN searching for the funniest film of the year, The Hangover has to be up there on the list.

It's not cleverly satiric or deeply intelligent - it's just a good concept played out hilariously and smartly by an excellent cast.

The one-line sypnosis is 'a group of guys go to Las Vegas for a bucks party and wake up the next day with no memory of the night before'.

The kicker is that their decimated hotel room contains a baby, a tiger and no sign of the groom-to-be.

Through the detritus in their pockets and the room, level-headed Phil (Cooper), panicky dentist Stu, and wacky nutjob Alan (Galifianakis) try to locate their missing buddy and piece together the mystery of the events of last night.

It's a "why haven't they thought of this before?" kind of plot, but in the wrong hands it could have been a wasted opportunity and gratuitously low-brow comedy.

Instead the script, which was partially re-written by director Phillips after the original screenplay was bought for a massive $2 million, dumps a whole bunch of amusing clues on the audience and casually unravels the answers with whip-smart deliveries from its stars.

The cast is part of the secret to this film's success. They get solid characters and swift lines, but they deliver them with great timing, particularly Galifianakis, whose eccentric Alan is the highlight of the movie.

The set-pieces don't always work, including a flamboyant Asian gangster they encounter, but most of them do because the audience is put in the same incredulous position as the characters and having 'what the?' moments as Mike Tyson sings Phil Collins' songs or one of the guys wakes up missing a tooth.

Simple but effective, The Hangover is an excellent idea perfectly executed and definitely of the funnier films of the year.