Infernal Affairs (2002)
"Mou gaan dou" (original title)

After a simple jewelery heist goes terribly wrong, the surviving criminals begin to suspect that one of them is a police informant.

As computer hacker Lisbeth and journalist Mikael investigate a sex-trafficking ring, Lisbeth is accused of three murders, causing her to go on the run while Mikael works to clear her name.

The discovery of a severed human ear found in a field leads a young man on an investigation related to a beautiful, mysterious nightclub singer and a group of criminals who have kidnapped her child.

A private investigator is hired to discover if a "snuff film" is authentic or not.

A sole survivor tells of the twisty events leading up to a horrific gun battle on a boat, which begin when five criminals meet at a seemingly random police lineup.

An ex-tennis pro carries out a plot to murder his wife. When things go wrong, he improvises a brilliant plan B.

In 1935, when his train is stopped by deep snow, detective Hercule Poirot is called on to solve a murder that occurred in his car the night before.

A shady police detective finds himself in the middle of a murder conspiracy at an important boxing match in an Atlantic City casino.

A congressman's daughter under Secret Service protection is kidnapped from a private school by an insider who calls Det. Alex Cross, sucking him into the case even though he's recovering from the loss of his partner.

Trainees in the FBI's psychological profiling program must put their training into practice when they discover a killer in their midst.

A psychiatrist comes to the aid of a compulsive gambler and is led by a smooth-talking grifter into the shadowy but compelling world of stings, scams, and con men.

An agoraphobic psychologist and a female detective must work together to take down a serial killer who copies serial killers from the past.