There are many famous pairings of directors and actors over the history of cinema. Teams such as Martin Scorsese/Robert Deniro and John Woo/Chow Yun-Fat have produced some of the most unforgettable films ever. And for a while starting in the mid-1990's, the duo of Johnnie To and Lau Ching-Wan was one of the most consistent in Hong Kong cinema.

Movies like Too Many Ways to be No. 1, A Hero Never Dies, and The Longest Nite not only proved that there was still life left in the world of Hong Kong film-making in the post-handover world, but the industry could still produce some of the most exciting and vital pictures in the world.

But in 2002, Lau stopped working with To, instead mostly concentrating on comedies, much to the chagrin of many fans. Well, kids, breathe a sigh of relief, because Lau Ching-Wan has once again joined up with Johnnie To with Mad Detective, and the result is one of the best Hong Kong movies of 2007.

In the film, Lau plays Bun, a detective whose unorthodox methods puzzle his fellow cops, but always seem to get results, so they tolerate his antics. But after Bun gives his chief (Eddy Ko Hung) a slice of his ear as a present, Bun is shown the door. Two years later, Bun's former protege Ho (Andy On) shows up to ask for his help in the investigation of a murdered cop.

It turns out Bun's odd behavior is caused by his ability to see people's true personalities, and it is through this that he is able to discern that the main suspect in the case (Gordon Lam) actually has seven personalites that have worked together to hatch a plan to cover up the crime. Ho begins to fully believe in Bun's "powers", but as things go on, it becomes apparent that Bun is just crazy and has been leading Ho on a wild goose chase... or has he?

Mad Detective offers everything one would expect from a To/Lau collaboration. It's quirky yet serious, whimsical yet given to bouts of extreme violence, giving the viewer one those experiences that could only truly be gotten from a Hong Kong movie. So why doesn't this film warrant a higher rating? That can be put squarely at the feet of Andy On.

On is good enough as a lead in fluffy pictures like Looking for Mr. Perfect and Dragon Squad, but he doesn't have enough weight as an actor to carry the role of Ho. The character should (and is made out to be) multi-dimensional and conflicted, but On's flat performance doesn't add any life to it. Thankfully, especially when offset with Lau Ching-Wan's incredible work here, it's not bad enough to totally derail the movie. But it does keep it from becoming a truly great film instead of "merely" a very good one.

RATING: 7.5