Danger could lure me as well.
Feng Shufen has always have been suspicious of his mother's death. Although he never had anything concrete in his hands, he never brought himself to believe that his mother was gone.
The house she was living in was set on fire and the police confirmed there was no life inside the place, and whatever was there had burnt into ashes. Still somewhere he felt that things weren't as they were showing on the surface.
And that suspicion in his heart was the reason why behind the curtains he had always kept people looking for evidence of his mother's existence. Although it took him years to get hints on that thing, finally he got something. How could he miss it when it was finally there after that long time?