CONTAINS SOME SPOILERS AND YET AGAIN CAN'T THEY GET THE DAMNED TITLE RIGHT?
If you pick up the DVD artwork for this nonsensical Hong Kong basherama you'll surely notice the title appears to be Assassin: City Under Siege but the word Assassin doesn't appear on the screen at any point. Why change it? There seem to be two reasons for it, neither of them particularly convincing. Firstly, they wanted to avoid it being confused with Police Academy 6: City Under Siege - but who can't tell the difference between an Asian martial arts fantasy and a knuckleheaded cop farce? Secondly, City Under Siege is not a wildly exciting title, and not a very accurate one either as the threat is within the city - but putting Assassin in front is even more inaccurate as there aren't any assassins in the movie. Frankly they might as well have called Abbott And Costello: City Under Siege because they aren't in it either.
City Under Siege starts off in Malaysia at the end of the Second World War where a mad scientist is conducting experiments with a mutation gas that turns people into superstrong monsters. Years later, some lunkheads from a travelling circus ransack the underground lab looking for gold, but they inadvertently release the same gas and are transformed into monsters - and only the wannabe knife-thrower, similarly affected but able to control his powers, and a TV reporter (Shu Qi), can stop them from thoroughly trashing Hong Kong.... Also involved are a couple of (near-married) agents who specialise in this kind of case and who can take on the mutants without superpowers of their own....
It's all a bit X-Men, all a bit Chronicle: absolute twaddle but rather good knockabout fun and generally very likable. The director is Benny Chan who really knows how to put thumping action sequences together - Jackie Chan in New Police Story, the cracking Invisible Target, or Connected (a vastly superior remake, with superb car stunts, of the okay Kim Basinger movie Cellular). To be honest City Under Siege isn't as much fun as those movies: the fantasy element means there's much more in the way of CGI and special effects which rather get in the way of extended scenes of people lamping each other, and I'm not a huge fan of wirework, preferring movies where the cast basically obey the law of gravity. But it's well assembled, entertaining nonsense.