Seven years prior to the main events, Cheung worked undercover within a notorious criminal gang led by the ruthless explosives expert , also known as "Blast". During a high-stakes heist, Cheung successfully exposed the gang, leading to the arrest of several members, including Blast's younger brother, Hung Kai-piu . However, Blast managed to escape and vowed to exact revenge on the man who betrayed him. The Revenge and Tunnel Siege
: Blast rigs the tunnel with 1,000 kg of C4 explosives . Seven years prior to the main events, Cheung
: He demands the release of his imprisoned brother and a massive financial payout from the government regarding tunnel stocks. The Final Confrontation Shock Wave Cheung successfully exposed the gang