Dublin metrosexual Fionan (Hugh O'Conor) is getting married... but doesn't want a stag party. When his concerned bride-to-be persuades the marginally more macho best man Davin (Sherlock's Andrew Scott) to organise one he reluctantly agrees. However, her alpha-male brother, known only as 'The Machine' (Peter McDonald), gatecrashes their sober, walking weekend and rural Ireland doesn't know what's hit it. Writer-director John Butler makes his feature debut with a sort of take on The Hangover, but less crack and more craic.
Reluctant stag Fionan (O'Conor) is persuaded to organise a country weekend away with his best buddies, including determined singleton and best man Davin (Scott), his gay brother and his partner.
However, they're also obliged to take along the bride's nutjob brother The Machine (McDonald), a loose cannon alpha male who revels in foul-mouthed rants and physical stupidity.
It's ripe to whip up into a perfect storm of mis-matched mates, bruised egos, camping faux pas and worse, particularly as The Machine fulfils the function of macho catalyst, needling his fellow groomsmen with insulting nicknames, broadsides at their sexuality and an insistence on public self-abuse.
However, it all turns out anti-laddishly genial and polite with Davin revealed to still hold a torch for the bride (his ex), The Machine having a soft side and the revellers a perfectly decent bunch of middle class chaps with a weakness for MDMA.
It makes a change from the tiresome antics of the wolf pack by the time the second sequel of The Hangover limped into cinemas (they don't even cavort with a convicted rapist) but it doesn't make for a split-your-sides comedy.
The acting is uniformly excellent and writer-director John Butler has an ear for dialogue yet the resulting mild diversion never does more than quietly amuse.