Infernal Affairs is a 2002 Hong Kong crime-thriller film directed by Andrew Lau and Alan Mak. It tells the story of a police officer who infiltrates the crime gang, and a police mole secretly working for the same gang. The Chinese title means "the non-stop path", a reference to Avici, the lowest level of hell in Buddhism. The English title combines the law enforcement term 'internal affairs' with a reference to Inferno, the Latin name for Hell. Due to its commercial and critical success, Infernal Affairs was followed by a prequel, Infernal Affairs II, and a sequel, Infernal Affairs III, both released in 2003.
Pre-release publicity for Infernal Affairs focused on its star-studded cast (Andy Lau, Tony Leung, Anthony Wong, Eric Tsang, Kelly Chen and Sammi Cheng), but it later received critical acclaim for its original plot and its concise and swift storytelling style. The film did exceptionally well in Hong Kong, where it was considered "a box office miracle" and heralded as a revival of Hong Kong cinema which at the time was considered to be direly lacking in creativity.
The Infernal Affairs series was then remade by Martin Scorsese in 2006 as The Departed, starring Matt Damon, Leonardo DiCaprio, Jack Nicholson and Mark Wahlberg. It went on to receive four Academy Awards, including Best Picture, a Best Director win for Scorcese and Best Adapted Screenplay for William Monahan at the 79th Academy Awards becoming the first and only remake of a foreign film to win Best Picture award.
The Prologue opens with the introduction of Hon Sam (Eric Tsang Chi-Wai), a Triad boss and the primary antagonist of the film. Sam is sending a number of young, green gangsters to the police academy as moles-- amongst them is one called Lau Kin-Ming (whose younger version is portrayed by Edison Chen Koon-Hei). At the same time another person named Chan Wing-Yan (whose younger version is portrayed by Shawn Yue Man-Lok) is shown joining the police force. Although he manages to impress the Superintendent Wong Chi-Shing (Anthony Wong Chau-Sang) and the police academy principal Yip, Yan is expelled from the academy. In reality Yan becomes an undercover reporting directly to only Wong and Yip. Yan's undercover job becomes stressful while Ming, on the other hand, is slowly rising up the ladder in becoming a top cop.
The film begins after Yan and Ming converse at a hi-fi store where Yan works, neither of them knowing who the other is. Soon after, Yan attends a funeral. It is revealed that Yip has recently died and that Superintendent Wong remains as the only person who could identify Yan as a cop. Later a deal between Hon Sam and a Thai cocaine dealer is interrupted by Superintendent Wong and his team due to Yan's tip-off using Morse Code. However, Ming alerted Sam of the bust with enough time for Sam to order his minions Tsui Wai-Keung (Chapman To Man-Chat) and Del Piero (Dion Lam Dik-On) to dispose of the cocaine so the police would not have any real evidence on the drug deal. Now, both Wong and Sam realize that they each have a mole within their respective organizations, putting them in a race against time to root out the other mole.
Later, Sam converses with Ming at a cinema with Yan watching. As Sam and Ming leaves, Yan tries to follow Ming. At the crucial moment, Yan's phone rings and he is forced to back off, thus losing his chance to capture Ming to the police department.
At the same time, Yan and Ming are both struggling with their double identity. Yan is starting to lose faith in himself as a cop after being a gangster for ten years; while Ming, on the other hand, becomes more and more used to the life of a righteous police officer and wants to erase his criminal background.
Later Yan meets SP Wong a second time on the same rooftop unaware that Ming has his subordinate, CIB Inspector B (Gordon Lam Ka-Tung) and his team tracking him down. Sam, after getting intel from Ming, sends Keung, Del Piero and a gang of henchmen to confront them. Inspector B informs Ming and he sends an OCTB squad to attempt to save Wong. Yan eventually escapes the building by taking the crane but Wong is caught by Del Piero and is thrown off the roof. As Yan is about to escape, he witnesses Wong's fall to death, and is stunned. As the police close in, a shootout between the police and Triads breaks out, resulting in the death of 3 Triads, one of whom is Del Piero. In the aftermath of the gunfight, the OCTB squad arrives with Ming and Wong's second-in-command Inspector Cheung (Berg Ng Ting-Yip) on the scene, but they are too late to save Wong. Yan and Keung manage to escape from the gunfight. As Keung drives away with Yan, he crashes the car, and finding that he is wounded from the gun battle, Keung dies in Yan's arms.
Eventually, Ming retrieves Wong's old cellphone and makes contact with Yan. They reach a deal to foil another one of Sam's drug deal. Inspector Cheung does not want to cooperate with the operation at first because of Wong's death, but he is later convinced by Ming to go ahead with the operation. With Yan's help, Sam's drug deal is interrupted and Sam is killed by Ming. Much of other Sam's gangsters are arrested. Everything seems to work according to the plan: Yan could now return to his true identity as a police officer and Ming has successfully erased his criminal connections by eradicating Sam and his gangs. However, back at the police station, Yan discovers Ming was the mole, and leaves immediately. Ming realises what has happened, and erases Yan's identity from the police computer records. Yan spends an evening with his therapist Lee (Kelly Chen), who he was falling in love with, and sends a compact disc to Ming's wife Mary (Sammi Cheng Sau-Man) with a recording that Sam kept between himself and Ming. The two agree to meet on the rooftop of the building where Wong was murdered earlier. Yan manages to disarm Ming and holds a gun to his head. Inspector B arrives on the scene shortly afterwards and threatens Yan to release his boss. The film ends with Yan entering a lift backwards with Ming hostage, when he is suddenly shot in the head and killed by Inspector B as he moved his head from behind Ming. Inspector B reveals that he was also a mole for the triads. He asks Ming for future protection and benefits since he is the only one who knows his true identity. As he and Ming enter the lift going down to the lobby, Ming shoots him dead thus ensuring his identity remains a secret. The original ending climaxes with Ming identifying himself to the police as an officer, and paying homage to Yan at his funeral, where he is buried next to Superintendent Wong. A flashback reaffirms the point that Ming wished he had taken a different route in his life.
An alternate ending of Infernal Affairs was created for mainland China, Malaysia and Singapore. The alternate ending has Ming exit the lift to be informed by Inspector Cheung that the police force have found evidence that he was a mole. He hands them his badge and is arrested without protest. This ending was meant to please mainland officials by affirming that crime does not pay. Versions of the DVD of the film may have one or both endings.
9th Annual Hong Kong Film Critics Society Awards
40th Annual Golden Horse Awards
8th Annual Golden Bauhinia Awards
Infernal Affairs was incorrectly called "a Japanese film" during the 79th Academy Awards, at which The Departed won four Oscars. Director Martin Scorsese corrected this in his acceptance speech for Best Director. An apology note on behalf of Warner Brothers was sent to Media Asia the following day.
The 2003 TVB spoof celebrating the Chinese New Year called Mo Ba To(吐氣羊眉賀新春之無霸道) and the 2004 comedy film Love is a many stupid thing(精裝追女仔2004) by Wong Jing were rewritings based on the plot of the film.
In Taiwan SHODA(劉裕銘) and a secondary school student Blanka(布蘭卡) cut and rearranged the original film and inserted new sound tracks to produce their videos Infernal Affairs CD pro2 and Infernal Affairs iPod on the web. The videos had many views and both producers removed their videos after received warning letters from the Group Power Workshop Limited(群體工作室), the Taiwan distributor of the film.
Media Asia released a limited edition of 8 DVD set of the Infernal Affairs trilogy in an Ultimate Collectible Boxset(無間道終極珍藏DVD系列(8DVD套裝)) on December 20, 2004. Features included an online game and 2 Chinese fictional novels of the film series by Lee Muk-Tung (李牧童)(無間道I+II小說 ISBN：9626722592 and 無間道III終極無間小說 ISBN：9626722711).