When a secret police operation fails, sniper Lee Ho-yeung develops a personal grudge towards his co-worker Ko Chun-kin. Ho-yeung eventually decides to leave the police force and becomes the president of a firearms association, colluding with organized crime on the sky. Through abusing the trust of an unknowing detective and the trust of his girlfriend who still works with the police unit, Ho-yeung has secretly been working against Chun-kin, who has been kept in the dark the whole time. But when Chun-kin starts to suspect the clues within multiple murder cases, a tense standoff between the brothers unfolds.

I membri di un eterogeneo gruppo di vigilantes formato per migliorare l'immagine della polizia vengono messi in pericolo quando si imbattono in un inaspettato affare di droga.

Chief inspector of Hong Kong’s Criminal Intelligence Bureau, Cheuk Hoi, is suspicious of his close colleague’s mysterious death. Adding to the enigma, he discovers that the five undercover agents who were in constant contact with his dead friend have all vanished.

La serie racconta la storia di un agente di polizia sotto copertura, Martin Hristov, interpretato da Ivaylo Zahariev, che viene infiltrato nell'organizzazione criminale di carattere mafioso guidata dal boss Petar "Dzharo" Tudzharov, interpretato da Mihail Bilalov. Si ispira parzialmente al film del 2006 The Departed - Il bene e il male di Martin Scorsese.