Line Walker

Charmaine Sheh plays a woman who is tasked with locating six mysterious undercover agents. With assistance from Q-sir, who is a smart and quick-witted cop, she once again infiltrates the triads. She faces the unforeseen dangers of the underground world and is pelted between two notorious gang members: an unconventional drug lord (played by Louis Koo) whose actions are always a mystery, and an unstoppable, calculating, coldblooded killer (played by Nick Cheung).

During her mission, however, she receives a shocking text indicating that a sixth undercover agent is either Louis or Nick. Determined to complete her task, Charmaine throws her life on the line and becomes tangled with the triads.