Many years ago, the anti-narcotics team sought to bring down a drug lord who goes by the alias "Lao Die". Before the operation, Lu Sir asked the four members of the team to turn in their phones but their precaution were for naught due to a trap waiting for them. While the four were once like brothers, everything can no longer be the same. Ah Feng as well as their superior Lu Sir are killed. Ah Tang disappears from the police force while the relationship between Lao Mi and Tai Hua have become very tense. Meanwhile, Lao Die becomes suspicious of his right-hand man Lao San. Although Lao San has been by his side for many years, he often provided information to Lu Sir in exchange for protection. Lao Mi and Tai Hua start to work together to capture Gouya who's shot dead by Lao San. Lao San then claims to be an undercover agent, saying that it was not only Zhou Sir who received bribes by back then. Tai Hua and Lao Mi must now fight to avenge their brothers...