After solving the narcotic case, Lee Tin Kin is promoted to a station sergeant and transfer to the TST station for temporarily replaced for the sergeant who is on annual leave. Lee’s sister Lee Tung with his boy friend KK Wong back to Hong Kong during school vacation and plan to engage. KK’s father Wong Pak Chuen is in charges of gang, since Lee is a justice guy, so his sister unwilling to let him know and would like to wait until appropriated timing. After well arrangement, Lee Tung decides to invite his brother to KK’s birthday party. Since a numeric of gang is also be present, Lee is so angry. He comes across his enemy who made him to shift to Yuen Long is also here, they have a quarrel and leave unhappy. From now onward, Wong & Lee are enemy. As Wong’s fellow Kwan Lik Kei fears his narcotic business will be discovered by Lee, he then assigns the murderer Tai Fei to kill Lee, Lee can escape on time. In the meanwhile, Lee Tung and KK get the evidence of Lik Kei selling narcotic, they then inform Lee & Wong. Their animosities vanish and collaborate together to deal with Lik Kei.