The magic rule for sequels seems to be: “If it worked the first time, don’t deviate from the original formula too much.”

That’s definitely what happened with The Hangover Part 2. A runaway hit in 2009, The Hangover emerged from a summer season of klunkers to become one of the top-grossing films of the year.

Check out the way Bradley Cooper, one of the cast members for both films, enunciated the formula.

“We made the decision early on to keep the same plot structure. I remember we did this photo shoot for Vanity Fair and that was when we first talked about a sequel in a realistic way; and we were all in the room together afterwards and we were saying, ‘Here’s the choice: do we stray from the structure or do we run straight for it?’

And we all agreed, no question about it, we hadn’t earned the ability to take these three guys out and put them in a new structure. There needs to be a ticking clock, there needs to be a missed night and there needs to be someone who’s gone and a woman who is waiting to get married and a guy who needs to get married.”

Cooper (The A Team, Wedding Crashers) is part of a quartet of guys who head off to Las Vegas to celebrate the upcoming wedding of one of their number in the original.

They end up totally drunk and disorderly, and with absolutely no memory of what has transpired on their debauch of the night before.

Moreover, they are missing the prospective bridegroom, and have somehow acquired an infant in their entourage. They must find a way to piece it all together, figure out what happened, and return in time for the wedding.

Hangover Part 2 follows the identical plot-line as the original, except that Thailand is substituted for Las Vegas, a monkey takes the place of the baby, and a different bridegroom goes missing.

Where the original film definitely had its comedic moments, the sequel opts instead for crudity, nudity and stupidity. Nonetheless, it looks destined to equal or surpass the box-office record of its predecessor.

Director Todd Phillips seems to play it safe with his plot-lines; his most recent film – last year’s Due Date – incorporated some of the same elements as Hangover, with a father on a deadline to return home for the birth of his child.

But Hangover 2 muddles too many elements together, while trying to incorporate as many characters from the original in order to strike a note of instant recognition with filmgoers.

Unfortunately, they are either superfluous to the main story-line, or their presence is gratuitous, as is the case with a cameo appearance from Mike Tyson, who at least had a tenuous relevance to the plot development of the original film.

The Hangover Part 2 plays at the Qwanlin Cinema at 7:15 and 9:15 pm and is rated 18A for sexually suggestive scenes and nudity.

Brian Eaton is a cinema buff who reviews current films and writes on other film-related topics on a regular basis.