In order to do the 4-way comparison of Infernal Affairs (2002) vs The Departed and other remakes, I rewatched the Infernal Affairs trilogy again.  Infernal Affairs III (無間道III:終極無間) (2003), the sequel to the original movie, while having a really ambitious story, is tremendously confusing and leaves questions unanswered.  I found that nearly 10 years after the release of this movie, there are very few, if any, plot analysis for it in English.  So I need to write one, for those who love the original movie and want to know what happens after that.

About Infernal Affairs III (2003)

Everyone wants to see more of Tony Leung’s performance, even after the death of his character in Infernal Affairs (2002).  In order to bring back his character CHAN Wing-Yan (hereafter Yan) from death, half of Infernal Affairs III creates new scenes before his death, and the other half concludes what happens to Andy Lau’s character LAU Kin-Ming (hereafter Ming).  To tie these together, two new characters are introduced: YEUNG Kam-Wing from Security Division of the police force, and SHEN Cheng, a mysterious gang leader.

The movie employs parallel storytelling in the two timelines, and jumps around in time with a large number of disjointed segments.  Most people’s first reaction of watching this movie is that it jumps around so much that it becomes confusing.  This is so bad that the trilogy later gets a 5-hour DVD release that rearranges the whole thing as a Chronological Edition.  Actually, on second viewing, this is no longer much of a problem.  However, the central problem is that the filmmakers chose to withhold or obfuscate important details in the story.


If someone thought Infernal Affairs (2002) spoon-fed the audience (this is not an assessment that I agree with), this movie is the extreme opposite.  To illustrate my point, in the climactic scene where we see Ming opening Yeung’s safe, there are very quick and brief cuts to a different pair of hands opening a safe, with a completely blurred face.  This blurred face is Yeung – he also opens Ming’s safe.

Audience outside Chinese circles may not know that there is an official novelization of the movies.  Although it helps to answer questions in the movie, the novel contains significant additions or changes to the movies, so it is not always the best suitable explanation for the movie.

Plot analysis

SHEN Cheng

Shen is a cop from mainland China.  Before Yan’s death, he poses as a gang leader and comes to Hong Kong to do business with HON Sam (hereafter Sam), in order to catch him.  He failed this objective but befriended Yan and Yeung.  After learning Yan’s death, he comes back to Hong Kong and helps Yeung expose Ming.  He also represents the Chinese police force and deals with Yeung in Hong Kong – China police matters.

YEUNG Kam-Wing

Yeung remembers Yan from the police cadet school as soon as catching him in the restaurant.  (And Ming as well, according to the novel.)  He trades information with Sam.  At the end of the movie, it is revealed that he setup surveillance cameras in Ming’s office (earlier than Ming does this in Yeung’s office, according to the novel).  In the movie, Yeung is a good guy.  In the novel, a lot of background is added to make him not so good.  In particular, the lines “The book ‘How to Get Rich in 1 Day’ is good” and “I’m not in need of money” for Sam and Yeung respectively in the library scene are swapped in the novel, which presents Yeung as a greedy cop who wants money from Sam, and is jealous of Yan because Yan, before being expelled, was the best performer in the police cadet school.  Most importantly, the novel says he approached Sam proactively to become a mole in order to further his stagnant career.  Only after he got promoted into the Security Division did he quit working for Sam but still traded information with him.


The Chinese title of the movie refers to a Buddhist view of eternal hell.  In the trilogy, there are shots of Buddha statues in elevator shaft, symbolizing people’s descent to hell.  It is especially relevant for the climax scene in the first movie, in which Ming shoots Billy (another mole working for Sam) in the elevator while descending.

Sauna scene – Yan damages everything

This scene reiterates Keung’s point of massage girls being beautiful is really important, just before he died in the car crash in the first movie.

Night club scene – Hitting Tai Wan gangsters

The night club scene introduces us to the Yeung character.  What is not obvious is that Yeung has the information on these Tai Wan gangsters because Sam tipped him off.  This is confirmed in the novel.

The key in Chun’s suit

When Chun (who works under Yeung in the Security Division) asks Ming to bring him his suit, a key is dropped.  Chun shoots himself after confronting with Yeung.  After Ming goes to the Internal Affairs office and discusses with Cheung, he realizes the key in the suit is for the bowling locker, so he goes back to take the key.  With this key, they unlocked pictures of Yeung meeting with Shen taken by Chun.

Unlikely alternative theory: Yeung puts those pictures in the locker as a bait for Ming.

Restaurant scene – Yan hitting Liang using an astray

The reason for Sam telling Yan to hit Shen’s (fake) brother Liang is that he does not trust the Shen gang.  In the actor’s words when explaining the movie to the press, Sam sacrifices Yan in order to find out what type of people the Shen gang is.  As revealed later in the movie, Sam sold Yan (along with the gangster) out to Yeung.

Other possibly valid reasons may include punishing that guy for verbally threatening Sam earlier, and to show him who’s boss.

Car park scene

Yeung finds out that Ming installed a tracking system in his car to track him.  So he proceeds with the postbox trap below.

Postbox with smoke

Since Yeung knows that Ming is monitoring him, he setups a trap by taking out a tape from his safe and dropping it to the postbox.  Shen cooperated with Yeung to watch Ming burn the postbox, in order to confirm that Ming is a mole working for Sam.  Since this is a trap, the content of the tape is not important, it may as well be blank.

Library scene – Sam meets with Yeung

We see Sam meeting Yeung and asks for help with something, which is not stated.  This is about Shen’s identity.  The novel explains that the library is chosen as a place that can avoid both cops and gangsters while having light, after ruling out Sam’s karaoke disco and the cinema.

Yan’s medical records

Upon reading Yan’s medical records, Ming becomes more schizophrenic and begins to identify himself as Yan, a good cop, free from eternal hell.  It is interesting to note that if you freeze the playback and read the medical record in detail, it is not about Yan at all.  This is likely a sloppy part in the film making.

Phone call from the dead Yan

In 2003 Ming receives a phone call from the dead Yan, who reports the meeting of Yeung and Sam.  It is clear that Ming is hallucinating, and this call is actually placed by Dr. Lee.

The tape sent to Dr. Lee

The only thing that is clear about the tape sent to Dr. Lee is that Ming wanted it so much that he crashed the car in order to get it.  Who sent the tape to Dr. Lee, and what is its content?  This is a major mystery in the movie for which there is no definitive answer, unfortunately.

Novel: The novel states that by this time Yeung knows Ming is schizophrenic and identifies himself as Yan.  So Yeung made a recording in morse code: “Listen, the current Chan Wing-Yan!  The tape you want is in Lau Kin-Ming’s safe in his office.”  This does not really work in the movie since there is no indication for Yeung to understand MIng’s schizophrenic condition.  Dr. Lee really has not listened to the tape because she is afraid, and she gave an excuse of not having a tape player.

Theory 1: Yan sent the tape containing the cinema conversation between Sam and Ming to Dr. Lee before going to meet MIng in the rooftop and getting killed.  Treating the tape as a property of Yan, Dr. Lee kept it but did not open it or talk about it until she became suspicious of Ming.  In the climax Ming played this tape when arresting Yeung.

Theory 2: Yeung sent this tape as another trap.  It contains a song and is played when Leung Sir examines Ming’s office after MIng shoots himself.

Arms transaction

Sam has never trusted Shen, so he does not go to the harbor for transaction.  Sam sold Yan out again.  By this time, Yeung has already found Shen’s identity (cop) at this time, so Leung Sir and him prevented Wong from carrying out the operation to catch Sam.

Where the tapes come from

In an early scene in the elevator, Ming recalls Billy telling him a bag of tapes were sent to Leung Sir (from Yan).  Luckily for them a mole under Leung Sir intercepted the tapes.  There is a theory that says this mole sent the corresponding tapes to the affected moles respectively.  This explains why Chun has a tape, two tapes of Ming show up, and one tape of Yeung shows up in the movie.

In the novel, it says the bag of tapes was mistakenly sent to Billy due to illegible handwriting.  Billy told Ming where the tapes were before getting killed by Ming.  Ming got the tapes and in an attempt to convince Mary that he is a good guy, he sent those tapes to the respective moles, causing them to commit suicide.  This scenario does not work in the movie.  In addition, the novel states that Yeung carries a device from Security Division that interferes with tape recording, so there does not exist any tape recording Yeung when he is working in the Security Division.

Safe opening

In the safe opening sequence we see Ming opening Yeung’s safe, but there is more.  As explained before, we also see another pair of hands – Yeung opening Ming’s safe.  Yeung got Ming’s tape then looks into a surveillance camera inside Ming’s office and said “Brother, you’re right” in Mandarin.  He left Ming’s office then phoned Ming and asked “Are you having fun in my office?”  Since Shen is the only cop in the movie that speaks Mandarin (while everybody else speak Cantonese), we know his words are meant for Shen.  This tape is then given to Shen to play just before Ming shoots himself.  This tape records the conversation between Sam and Ming after Wong’s death in the first movie.

Tapes in the climax

When the movie was shown in Hong Kong theaters, and in the first version of Hong Kong DVD, we see Ming playing a tape in his own office after stealing one from Yeung’s safe, and we hear the library conversation between Sam and Yeung.  Then he stops the player, and puts it into his right pocket and goes out with his team to arrest Yeung.

When he sees Yeung, he plays the tape in his left hand.  Although we expect to hear the library conversation, we hear the cinema conversation between Sam and him instead.  This creates the single greatest confusion in this movie.  Why the contents are different when they should be the same?

Theory 1: In this theory Ming played different tapes in his own office and when arresting Yeung (but neither is the the one stolen from Yeung’s safe).  The tape in the office is put in Ming’s right pocket.  The tape he actually played in front of everyone is in his left pocket, it is either originally in Ming’s safe or obtained from the car crash with Dr. Lee.

Theory 2: In this theory Ming played the same tape (but not the one stolen from Yeung’s safe), but what we hear initially in the office is actually Ming’s hallucination.  This tape is either originally in Ming’s safe or obtained from the car crash with Dr. Lee.

In the novel there is no such confusion, because the novel does not reveal what Ming heard when he played the tape in his office.  I guess that upon the release of the movie, the filmmakers realize this is an unexplainable confusion, so they changed the later versions of the movie, including the Chronological Edition Hong Kong DVD, and the Blu-ray version I watched, to mute the tape playback inside the office.  We still see Ming stopping the playback, but we don’t hear any words, only the background film music is present.  While this is not really a satisfactory choice, it eliminates the unconvincing hallucination part in theory 2.  This appears to be the filmmakers’ choice and is consistent with the novel, in the absence of better theories, perhaps we are forced to accept this.

In any case, it is very unlikely for Ming to play the tape he actually stole from Yeung’s safe, because Yeung cannot possibly have a tape that contains Ming’s conversation with Sam, otherwise he would have arrested Ming in the first place.  Then why go through all that trouble to steal one?  By now, Ming is crazy, identifies himself as Yan, a good cop, and thinks Yeung and “Lau Kin-Ming” are the same bad guy having two different names.  So which tape he plays does not make a difference to him at that point.  In short, he is crazy.  Perhaps the tape stolen from Yeung contains only a song so it cannot be used for arresting.  Yes, I know this is still unconvincing, but I don’t have any better explanation.

Unlikely theory 3: Ming discovered that one of his own tapes, which are strong evidences, was stolen by Yeung.  Comparatively, the tape stolen from Yeung containing the library conversation is a very weak evidence.  So he decides to play his own tape, act crazy, and shoot himself in a way that does not kill, to avoid jail.  I don’t think this theory makes any sense because it contradicts the early scenes with Ming hallucinating.

The last tape with the song

The last mystery is, where does the tape containing the song come from?  It is played when Leung Sir is examining Ming’s office after Ming shot himself.

Theory 1: It is stolen from Yeung’s safe.

Theory 2: Yeung previously sent this tape to Dr. Lee as the second trap for Ming.

Theory 3: It is one originally in Ming’s safe.

The problem with theory 2 and 3 is that then we don’t know what is recorded in the tape in Yeung’s safe that toke Ming so much trouble to steal.

Theory 4: The filmmakers think it is an artistically brilliant idea to have the song played at this point, they really don’t care about what contents are on what tape, and believe that letting Ming become crazy automatically eliminates all problems the audience may have with the tapes.  Those who spent time to over analyze the movie and write plot analysis FAQ are just crazy fools.