Unriddle

A rich Indonesian girl disappears and the police have been asked to look for her. Officer Hu Xiaoman go in search for her and discover a human trafficking ring as well. The ring-leader Shan Fan and his partner Lin Zhengyi escape, but Xiaoman recognizes Zhengyi's back view.

Xiaoman catches Zhengyi but Yuze interferes. It turns out that Zhengyi is Yuze's mole. In the plan, something goes awry, and someone dies because of Zhengyi. Guilt-ridden, she vows that she doesn't want to be a mole again after this.

Yuze, Zhirong and Andrew go and pay their respects to Old Cai. They see Wu Guosheng there as well, and are reminded of the events 15 years ago. Zhirong tells Yuze he feels that Guosheng has been following him, and Yuze feels uneasy.

Yuze chases Shan Fan, and Zhengyi later sees Shan Fan using the money to bribe Yuze in hope that Yuze will let him go. In the midst of chaos, Zhengyi realises that Yuze and Shan Fan have disappeared, along with the money. Only a patch of blood is left behind.

Zhirong searches Yuze's flat and is questioned by Andrew. Zhirong shows Andrew a threatening note left behind in the flat. Andrew suspects that this may have something to do with the case 15 years ago. Andrew decides to tell everyone that Yuze succumbed to corruption and disappeared.

Xiaoman starts to investigate Xiuling's case and along the way discovers the sacrifice Xiuling's father made to look for her after she went missing. Xiaoman explains to Xiuling that what her dad did was because he loved her. Father and daughter were reunited.