Line Walker

Hong To Hang dies after tumbling from a building, marking a brutal start to the case. As he dies, he warns Cheuk Hoi that moles are embedded within the force. He also deletes the files of five undercover officers to shield them from retaliation, setting a high-stakes trap for Hoi. This moment forces Hoi to confront a hidden danger within the police.

Guided by Hong's dying words, Hoi refuses to wait for official guidance and sets out on a solo mission. He vows to locate the missing undercover agents before the shadows close in. This marks a shift from formal channels to personal risk and determination.

Ting Siu Ka runs a quiet foot massage parlor that serves as the surface-level front for deeper undercover work. She becomes Hoi's new handler, tying his fate to the broader underworld network. Their alliance anchors the investigation and foreshadows tension with Bao Seed.

Bao Seed works with Ting Siu Ka on missions for Foon Hei, revealing his deep cover within the operation. It is disclosed that Bao Seed is another undercover set in place by Hong, complicating loyalties within the team. The revelation heightens risk as the line between ally and enemy blurs.

Ada appears as an undercover thread with a past connection to Hong, clarifying the mission's true purpose. Her presence adds another layer to the group of undercover agents under Hoi's watch. The AI-enabled dimension hints at a technologically enhanced web of loyalties.

Kobe Lin Ho Kan operates as a crooked stock broker to infiltrate triad circles and access Chum Foon Hei. After a prison stint to deepen his cover, Kobe earns an invitation to join Foon Hei's organization. This arrangement strains his relationship with Mok Sin Yan as trust becomes a scarce currency.

Yan grows wary of Hoi's rapid ascent and starts scrutinizing his moves. Her suspicions deepen as cases appear to go sideways, fueling the fear of exposure within the force. The tension between professional ambition and caution becomes a persistent undercurrent.

Hoi secretly becomes involved in Yan's sister Katie Mok Sin Ching's life, helping her escape an abusive marriage. This personal intervention tightens their bond but also threads their fates closer together. Their growing closeness adds complexity to their professional missions and the danger they face.

As Ting Siu Ka continues to work with Bao Seed on missions for Foon Hei, she senses a deeper complexity in the operation. A crucial revelation emerges: Bao Seed is not merely a separate component but another undercover set in place by Hong. The twist intensifies the web of loyalties surrounding Hoi.

Foon Hei's son dies as a consequence of his own misdeeds, triggering a slow transformation in the triad leader. The event unsettles Hoi and pushes the investigation toward a reckoning about who can be trusted. The turning point hints at shifting allegiances within the operation's core.

Hoi centers his suspicions on Yip Siu-leung as the potential mole. Kobe warns Yan about Siu-leung's possible treachery, though she initially dismisses the warning as jealousy. She decides to pursue the lead, setting the stage for a dangerous investigation.

Siu-leung confronts Yan with deadly intent on a rooftop, threatening her life. Kobe intervenes at the last moment, tackling Siu-leung off the roof and saving Yan. The rescue crystallizes the stakes for the undercover operatives and the peril of exposed loyalties.