Directed by Todd Philips. Starring Bradley Cooper, Ed Helms, Zach Galifianakis, Justin Bartha, Jeffrey Tambor, Ken Jeong, Paul Giamatti 16 cert, gen release, 102 min

‘IT’S HAPPENED again,” cries a panicked Bradley Cooper. Too right it has.

Having grossed more than $467 million on the back of a modest $35 million budget, Warner Bros announced a sequel to its 2009 sleeper The Hangoverwhile the original was still in theatres. The studio did well to nab the largely unknown cast when it did: Cooper, Helms and Galifianakis have all graduated to bigger and better things in the interim.

Unhappily, the new film is festering with symptoms of sequelitis. Cruder, zanier and way more expensive, The Hangover Part IItakes the wolf pack to Thailand, where Stu (Ed Helms) is scheduled to marry new girlfriend Lauren. One amnesiac evening later, and the groom wakes up in a scummy Bangkok flophouse alongside his equally befuddled old pals Alan (Zach Galifianakis) and Phil (Bradley Cooper).

But wait: where has Teddy, a teen prodigy and Stu’s brother- in-law to be, got to? And why is Teddy’s finger in a bowl? And how did the gang acquire a smoking monkey wearing a Rolling Stones jacket? Stop us if you’ve heard this one before.

It doesn’t take long for the gang to slip into a pale re-enactment of their Vegas adventures. Surface details have changed – instead of a baby, they acquire an ancient Buddhist monk; instead of losing a tooth, Stu is adorned by a tribal facial tattoo; instead of Heather Graham’s happy hooker, we get a Thai ladyboy. But the song remains exactly the same.

Seemingly determined to give the people what they want, Ken Jeong's demented Korean-American gangsta enjoys an extended role and Mike Tyson pops up before the final reel. These minor innovations do little to dispel the notion that this is a cheatquel hailing from the same axis of opportunistic evils that once yielded Revenge of the Nerds II: Nerds in Paradiseand the later instalments of the American Piesequence.

We might forgive the repetition if Hangover IIwas funny enough. But in common with many Bangkok travellers, the franchise has lost its witty innocence. In lieu of fun we get sordid stag set pieces, casual racism and a discombobulating reliance on homophobia.

It’s all a bit much from a project that fired Mel Gibson for not being politically correct.