Inspector Gordon Heung (Michael Miu) is loyal to a fault – so much that when an informant extorts him with info on his friend's illegal activities, he's willing to dirty his hands with drug trafficking. But nothing gets past his protege Wai Sai Lo (Raymond Lam), who quickly grows suspicious of his partner's off-duty activities. Meanwhile, the stakes get higher when Inspector Poon Hok Lai (Ben Wong) corrupts Wai's paramour Pat Chan (Kate Tsui) and forces her into drugs. Is there anyone Wai can trust?