Rui En (An Xiaoqian), Thomas Ong (Hu Xicun), Chen Han Wei (Ouyang Li), Terence Cao (Di Lun), Yvonne Lim (Wen Wanrou), Chen Guohua (Cao Zhongming), Julian Hee (Da Meng – Meng Tianbao), Ng Hui (Mya Sun Meiya), Ix Shen (Ryan Hou Lai En), Nick Shen (Zhang Shaoqi), Hong Huifang (Ouyang Su), Richard Low (Black Bear – An Guoxiong), Brandon Wong (Rattlesnake), Ong Aileng (Blood Rose), Wu Luoyi (Ghost), Huang Yiliang (Red Pig), Cavin Soh (Jin Yongjian/Cai Chengkun), Adam Chen (Ke Mingde), Rayson Tan (Zhao Shiqiang), Bryan Wong (Leon), Chew Sin Huey (Li Meixin), Alan Tern (Liu Hansheng), Carole Lin (Melinda), May Phua (Gina), Nat Ho (Wen Pinliang)
Members of the secret society are fighting for power. Assassin Swift Blade has already murdered two secret society leaders. Detectives Ouyang (Chen Han Wei) and Di Lun (Terence Cao) manage to corner Swift Blade. Xin Mei, mistress of secret society leader Rattlesnake (Xiang Wei She) (Brandon Wong), is held hostage by Swift Blade. Ouyang (Chen Han Wei) decides to open fire at Swift Blade, causing Xin Mei to die as well.
Xin Mei’s death infuriates Rattlesnake, resulting in Red Pig’s (Hong Mao Zhu) (Huang Yi Liang) death by four bullets. Rattlesnake is arrested by the police. However, the police discover that Rattlesnake is not the murderer after all. The true suspect behind the murder appears to be Blood Rose (Xie Mei Gui) (Ong Ai Leng), Rattlesnake’s wife. Blood Rose has always been bitter about her husband’s affair and has every reason to set a trap to let Rattlesnake and Red Pig bring harm to each other, while letting Rattlesnake take the blame for murder.
However, Red Pig’s real murderer turns out to be someone unexpected. When the police are hot on the heels of the murderer, they discover that the latter has been killed. The method of murder is exactly the same as Red Pig’s: four bullets shot directly to the body. There is even evidence leading to the identity of this new mysterious killer. It appears that someone has been carrying out capital punishment in secret…
While investigation of the identity of the killer continues, news of a horrific murder comes about once more. A dismembered female body has been discovered. The police suspect that Jin Yong Jian (Cavin Soh), boss of a mechanic workshop, is the murderer. Yong Jian is a patient of Wen Wan Rou (Yvonne Lim), a psychiatrist, and has fallen in love with her. The police arrest him, but discover that Wan Rou has disappeared at the same time. They suspect that Yong Jian has captured Wan Rou before he was arrested.
Ouyang and his team try every means to force a confession out of Yong Jian with regards to Wan Rou’s whereabouts. The case complicates further when they discover that he has split personality disorder. Finally, Wan Rou is successfully rescued, but she has already suffered irreparable trauma.
During an operation to hunt down the mysterious killer, Ouyang unintentionally causes an accident, taking the lives of Wan Rou’s father and younger brother Pin Liang (Nathaniel Ho). Her mother was so affected that she fell sick and passed away. Wan Rou is thrown into sudden darkness from the painful loss of her family. Her life begins to change dramatically…
The mysterious killer captured by Ouyang has been silenced by someone else. As the police investigate the identity of the killer, they slowly uncover the presence of an organisation known as Dragontooth. This mysterious group has apparently been carrying out acts of ‘justice’, meting out capital punishment to criminals who they deem deserve to die…
At this point, a male body is found, exposing a complicated string of love affairs between the protagonists involved in the case. The deceased is Leon (Bryan Wang), a male prostitute. He had a girlfriend as well as several love affairs. Everyone involved in this case seems to have a motive for murder, creating more complexity and confusion. One of the suspects, Melinda (Carole Lin), is murdered soon after.
After an intensive investigation by the police, they arrest Gina (May Phua), Gina had suspected her husband, Zhao Shi Qiang (Rayson Tan), of having an affair with Leon and had killed Leon in a fit of jealousy. Just when everyone thinks that the case has been solved, Dragontooth strikes again to mete out disciplinary action on the real killer. The truth is thus revealed; Gina did not murder Leon.
Ouyang and Di Lun chase down the clues to the case. They suspect that Ryan (Ix Shen) is a member of Dragontooth and forensic expert Hu Xi Cun (Thomas Ong) is in fact the leader of Dragontooth.
An Xiao Qian (Rui En) sets a trap for Xi Cun to lure Ryan out so that Dragontooth can be captured in one swoop. They manage to capture Xi Cun successfully. At this moment, Ouyang receives a call to that his foster mother Ouyang Su (Hong Hui Fang) has been held hostage by Dragontooth. Ouyang is made to promise to rescue Xi Cun. With no other choice, Ouyang agrees and saves Xi Cun. However, he has already become a common enemy of Dragontooth. Not long after, Ryan’s body is discovered. At the scene of the murder, numerous evidences found point towards Ouyang as the murderer.
The police hunt down Ouyang. Ouyang, unwilling to admit defeat, becomes a wanted man. He secretly carries out his own investigations and discovers that someone close to him is involved with Dragontooth and framing him for Ryan’s murder!
Xi Cun also finds out that a member has been going against Dragontooth’s principles in the quest for revenge. Now, he plans to discipline this errant offender with capital punishment personally…