Line Walker

Cheuk Hoi (Michael Miu) is a Chief inspector of Hong Kong's Criminal Intelligence Bureau (CIB) police unit. He is a righteous supervisor that will resort to unethical tactics in order to restore the identities of his undercover subordinates who have gone missing and deemed by the police department to have strayed to the criminal side. When he finds his friend Hong To Hang, a fellow Chief inspector in the CIB unit, thrown off a building under mysterious circumstances, he learns from Hong's dying words that there are moles within the police force working for the triads. In order to protect the lives of his five undercover agents, Hong has deleted their files from the police database, erasing their identities as police officers. Hong charges Hoi with the task of finding each lost undercover agent, but dies before he can tell Hoi any further information. Remembering Hong's warning against trusting anyone in the police force, Hoi keeps Hong's last words hidden from his superiors. Instead, he sets out on his own to find Hong's five undercover agents. With clues left behind by Hong, Hoi finds undercover agent Ting Siu Ka (Charmaine Sheh) who fronts as an owner of a foot massage parlor, and assumes his role as her new handler. Siu Ka's only assignment under Hong was to gather intelligence but Hoi assigns her the task of helping him find the other four undercover agents. Siu Ka decides to get close to Sit Ka Keung (Raymond Lam), nicknamed Seed who is part of an illegal gambling gang. He fronts as an ice deliveryman but is actually in charge of collecting unpaid gambling debts. Siu Ka previously clashed with Seed and his partner Muk Sut when they went to her shop to collect a gambling debt but becomes friendly with them because she knows of their connection to a major triad organization. Meanwhile Kobe Lin Ho Kan (Sammy Sum), another undercover agent working for Hong, fronted as a crooked stock broker in order to go to prison and get close to triad boss Chum Foon Hei as the last assignment he received from Hong, but Foon Hei soon proved to be a cunning target. Unable to gain any traction with Foon, Kobe believed he had failed his assignment. However upon Kobe's release from prison, Foon Hei asks Kobe to join his organization. In order for Kobe to follow through with his undercover assignment, Kobe sacrifices his relationship with ICAC officer Mok Sin Yan (Sharon Chan), who is unaware that Kobe is an undercover agent. ICAC officer Yan investigates Hoi because she suspects that he is a dirty cop with connections to the triads because of his fast raise in the police force and all the cases he is assigned to as the Chief inspector gets foiled. With Yan tracking his every single move, it makes things complicated for Hoi to meet up with the undercover agents. In order to keep one step ahead, Hoi bugs Yan's personal belongings and overhears her personal life. Accidentally he discovers the abusive marital life of Yan's older sister Katie Mok Sin Ching (Elena Kong). While helping Katie to escape her abusive life, the two begin to get closer and eventually begin a relationship.