Master Shan is a locksmith, and took on an apprentice Hao Ren before he developed dementia. Hao Ren inherits Master Shan`s exceptional locksmithing skills and becomes a master at opening locks, even surpassing his mentor. Because of this, the police often calls for his help, and this leads to a friendship with Officer Liu Ye Chen. A series of strange events starts to unfold when he meets up with an old friend and learns that the mysterious case surrounding Master Shan`s wife`s disappearance is far from straightforward.