"Informant" is a 2010 Hong Kong police action film directed by Lin Chaoxian and starring Nicholas Tse and Cheung Cheung Fai, for which Tse won the Best Actor Award at the Hong Kong Film Awards. The film was used by the cast and crew behind the 2008 film Witness. The film seems to be a sequel to "Witness", but the production company claims that this film and "Witness" are original stories that are "completely different", in order to bring greater dramatic shock to the audience.
Lin Chaoxian said that before the filming of "Witness", the inspiration for the plot of "Informant" had been generated. Lin continues the themes of "Witness" and "Fire Dragon" to explore human nature, demons, feelings and fate, describing whether the police will choose to be a "good policeman" or a "good person" for the sake of conscience when dealing with the lives and deaths of informants who are in danger and leaking for them.
In the process of monitoring the transaction of the drug lord Xiao Dog, Li Cangdong, senior inspector of the Criminal Intelligence Division of the Hong Kong Police Force, ordered the subordinate Gu Zai, who had infiltrated the transaction at that time, to arrest people on the spot in order to prevent the dog from destroying evidence, but in the end, the dog escaped, and the informant who was undercover next to the dog also exposed his identity. When he returned home that night, he bumped into the dog who had brought people to take revenge, and although he recovered a life after being slashed several times, he was deranged and lived on the street. Cangdong was promoted for solving the drug case, but at the same time he felt very guilty about the waste. A year later, Hua Tian, the leader of the jewelry robbery gang from Taiwan, returned to Hong Kong to prepare for a new stove, and Cangdong was ordered to send an informant to infiltrate the Huatian gang to collect intelligence and prepare to arrest him during the Huatian operation.
Cangdong checked from under Hua Tian's confidant Taiping and selected he Xikui, a car thief nicknamed "Thin Ghost". In order to pay off his father's debts, the ghost was bent on redeeming his sister who had been arrested for prostitution before committing a crime and going to prison. Cangdong meets with the ghost who is serving a sentence in the Wall House Prison and promises to give him a million informants after the matter is completed. The ghost was originally reluctant to cooperate with Cangdong, but after he was released from prison, he could not save his sister by brute force, so he had to join a night racing car according to Cangdong's instructions to gain Taiping's appreciation and join the Huatian gang. In the car race, the skilled ghost easily maintained the first place, but encountered a police barricade in the tunnel, and after the other drivers were arrested, the ghost successfully escaped under the secret coordination of Cangdong, signed the contract and officially became an informant, and officially joined the Huatian gang as a driver after receiving the contact from Taiping. He accompanies Taiping to meet three other members—the motor, the popper, and the zipper," including Huatian's woman, Adi, who had a relationship with her a few years earlier, when the two happened to be chased and inadvertently saved each other.
Cangdong followed Huatian's mobile phone signal through the intelligence of the ghost, leading the police to secretly track Huatian on the road. But the scheming Huatian felt that he was being followed, and Gu Zai was accidentally exposed when he was stalking, so Huatian quickly walked to a parking lot and threw away his mobile phone, coercing a female driver and hiding in her car to sneak away. After trading six guns for robbery from an arms dealer, the ghost and Adi were forced to run through the barricades of the police on the way back, and after a car accident, they had to abandon their cars and run to a market to hide in a cupboard before escaping. However, after a few days of getting along, Adi fell completely in love with the ghost and kissed him during the period of hiding. When Cangdong and the informant Waste Dog were alone, he learned that the Dog had reappeared, and in order to let the Dog Return to his family, he drove him to the Dog's hiding place, so that he could witness the Dog being caught by the police, and then let him feel at ease to go home and reunite with his wife.
In addition to business, Cangdong would visit his wife, Ah Xue, who was unable to give birth normally because of syphilis, and jumped off the building to cause lameness and amnesia due to the bad news for a while, and then worked in a dance classroom. Cangdong keeps visiting her because he feels guilty about her, but one day he is discovered by Ah Xue's father. Ah Xue's father beat Cangdong because he was afraid that his daughter would remember the past, but it caused Ah Xue, who was standing on the sidelines, to be frightened and run out and was seriously injured by a car, which made Cangdong suffer a big blow. On the other hand, after Taiping led his men to get rid of the stalking police, they began to arrange the next day's robbery plan, and the zipper wanted to pay more, which led Huatian to order the ghost and others to kill him. Due to the lack of manpower, the ghost could only listen to the order to take a gun. That night, Hua Tian had an argument with Adi because he had a mistress outside, and the two decided to part ways after the matter was completed.
The next morning, Huatian and his gang robbed Jingxin Jinxing, which had not been mentioned in the family's plan, and although the ghost secretly asked a roadside car driver to inform Cangdong, Huatian still stole gold weighing up to 250 kilograms before the police arrived, and before leaving, he shot Gu Zai and got into the car to escape. When the gang returns to the hiding place to dissolve the gold, the ghost calls Cangdong by a mobile phone and asks him to trace the location of the signal. During the melting of gold, Adi and The Explosive Beads betrayed Hua Tian and the others and prepared to take all the gold with them, but Taiping burned the Explosive Beads alive with fire, causing an exchange of fire at the scene. In order to protect Adi from being shot, the ghost and Adi fled the scene with a bag full of gold, and Taiping and Mada also burned all the crime tools and fled together. After the police arrived at the scene, Hua Tian, who was alone, was caught by the police, but because the evidence of the robbery was destroyed and Hua Tian could not be prosecuted, the boss ordered Cangdong to have the informant testify in court. Cangdong does not want to let the informant take risks and fall into a dilemma, but after learning that Ah Xue has died that night, he tries to commit suicide by crashing a car without success, and decides to save the ghost.
When the ghost and Adi were hiding in the mountain village, they confessed their identity as informants to her, but Adi refused to give up the ghost and called a doctor to treat him, not knowing that the doctor actually called Taiping and Mada to settle the account. The ghost and Adi ran to an abandoned school, and Taiping and the others fought with the head and blood, the fish died in the net, Cangdong arrived and joined the struggle and strangled the motor, after Adi hacked Taiping, he found that the ghost had been stabbed several times and died. When the police arrived, Ah Di handed over the gold and turned himself in to testify against Hua Tian's various crimes on behalf of the dead ghost. As Huatian is finally brought to justice, Cangdong obeys the wishes of the ghost and uses money to pay off his debts and release his sister, while he himself eventually faces arrest from his superiors for shielding informants, acting privately, and killing suspects.