The Detective is a 2007 Hong Kong neo-noir mystery thriller film directed by Oxide Pang, and starring Aaron Kwok as a private investigator hired to track down a missing young woman who may be linked to a series of murders in Thailand.

One day, a guy nicknamed Fatty asks Tam to find a lady who wants to kill him.

He leaves Tam a portrait and a large amount of cash without giving any other details.

As Tam continues to search for other mahjong playmates of Sum, he is shocked to find each of them murdered every time he is about to contact with them.

Tam realizes the suspicions behind the deaths and decides to protect the next target of the invisible murderer.