“Accident” is a dangerous film. This brisk, stylish thriller starring Louis Koo operates on the premise that none of the fatal “accidents” you see on the news are accidents at all—but rather, complex death traps.

The film follows the lives of four assassins who delicately set up these “accidents” –The Brain (Koo), The Woman (Michelle Ye), Fat Man (Lam Suet) and Old Man (Fung Shui-fan). They can kill with a falling piece of glass, a few balloons, a tram track or even just a kite. To The Brain, every accident can be planned. But what goes around comes around. When the team gets involved in an accident themselves while conducting a job during one rainy night, The Brain snaps and is convinced that they will all soon be killed in planned “accidents.” The film then switches gears to follow The Brain as he stalks an insurance agent (Richie Ren) whom he thinks is targeting his team. Director Soi Cheang, who masters the pace and storytelling of the film in the first half, shows his true talents in the second—Cheang carefully follows The Brain as he approaches the truth, but does so with a restraint that keeps the audience guessing along with him.

“Accident” is another addition to a new “Mad Detective” sub-genre of Hong Kong films wherein a man on the verge of insanity is forced to solve a puzzle that may or may not save him. We saw it with Lau Ching-wan in the first in the genre, “Mad Detective” (2007), and with Aaron Kwok in the appalling “Murderer” earlier this year. Local filmmakers seem to have fully embraced this new genre, but it only really works when the actor manages to pull off what is largely a one-man show. Fortunately, just as he did in his mold-breaking performance in “Overheard” earlier this summer, Koo once again shines as a serious actor, virtually erasing the cheeky idol image he’s known for. With “Accident” being his third big blockbuster of the summer, we’re going to go ahead and call 2009 the year of Koo.

4/5 Stars by Winnie Yeung.

Hong Kong. Directed by Soi Cheang. Starring Louis Koo, Michelle Ye, Fung Shui-fan, Richie Ren. Category IIB, 89 minutes. Opened Sep 17.