An explosion takes place in an apartment late at night, detective Ngai Wan (starring Ray LUI) arrives for the investigation and a charred woman body found on spot, her name is Yin Ching (starring Stephy TANG). Ching is getting married with Ng Lam who grew up in a wealthy family. Though it seems to be an accident, Wan feels that something is unusual.

Wan first investigate the background of Ching and finds that her mother was died in a fire accident fifteen years ago also. Before that, Ching and her mother were in a difficult relationship, Lo Chi Fung (starring Jasper LIU) was the only person Ching could talk to. They both grew up in Pak Sin Town and disappeared together after the accident happened.

Wan perseveres in the investigation but the case just like falling into the mist as everyone related to Ching are all hiding some secrets. The turning point comes out until Lo Chi Fung and his girlfriend Lam Yam (starring Stephy TANG) show up.

The two fatal cases are crossing fifteen years, everyone can be suspected. The truth is far beyond everyone's imagination behind the foggy surface…