Question: Extract the answer to the following question from the movie plot. If the question isn't answerable, please output "Can't answer". Question: Who tries to arrest Lau? Title: Infernal Affairs III Movie plot: Infernal Affairs III uses parallel storytelling, flashing between the past and the present. Six months before Chan's death[edit] Undercover cop Chan Wing-yan seeks to uncover the link between Hong Kong triad boss Hon Sam and the mysterious Chinese gang leader Shen Cheng. Since Hon's ascension to the seat of triad boss was due to the death of his predecessor, Ngai Wing-hau, Hon is suspicious of all his men for fear they might usurp his position. He tests Chan's loyalty by ordering him to smash an ashtray on Shen's brother during a negotiation, resulting in Chan's arrest by Inspector Yeung Kam-wing. Yeung tells Chan that though Chan does not recognise him, he recognises Chan and he warns the latter to "be careful". Chan is released after both Hon and Shen fetch him at police headquarters. Concurrently, Chan is prosecuted for violent behaviour. His superior, Superintendent Wong Chi-shing, persuades the court to allow Chan to seek therapy, leading him to meet Dr. Lee Sum-yee. Hon asks Chan to deliver arms to Shen, but he and other triad members do not show up. When Chan delivers the cargo, Shen's men discover that the boxes are empty and open fire on Chan; Shen and Chan shoot each other in the limbs during the crossfire. Shen finds out that Chan is an undercover cop when Yeung unexpectedly arrives on the scene. Yeung tells Chan that Shen is also an undercover cop, working for Chinese authorities. Yeung also tells Chan that he gained top honours when he was in the police academy due to Chan's "expulsion". The three shake hands and wait for the chaos to subside before leaving. Ten months after Chan's death[edit] Lau Kin-ming (Andy Lau), Hon's former mole in the Hong Kong Police Force, has been demoted to administrative duty pending an investigation into the deaths of Chan and Inspector B. He falsely claims that B shot Chan in the head while holding him hostage, and that he killed B in retaliation. After months of investigation, Lau is transferred back to Internal Affairs, where he struggles to whitewash his past...
Answer:
Second-in-command