Line Walker reunites Raymond Lam and Charmaine Sheh, who had not collaborated for a long time. Their characters are both undercover police in the triad world. Even though they don’t know each other’s true identities, they fell in love. As CIB (Criminal Investigation Bureau)’s Chief Inspector, Michael Miu will also be romantically involved with Elena Kong’s character. In contrast to other police dramas, the story also has comedic elements.