into the enigma of a perplexing disappearance case, leaving the master locksmith "Shu Shi" (interpreted by Xu Huanxiong) mourning the loss of his beloved wife "Sha Shi", and the orphaned childhood of detective Zhang Yijing (portrayed by Gao Haining). The story unfolds as Shu Shi, once a skilled locksmith running a renowned shop named "Credit", falls into senility following this incident. He takes on an apprentice, A Rin, who masters the art of opening locks under his tutelage, even surpassing his teacher's abilities.
A Rin often assists the police with his unique skills, befriending detective Li Ye Xin (portrayed by Huo Haoren). Despite being unable to open a lock in his career thus far, A Rin encounters an old acquaintance, Li Quan Kai (portrayed by Chen Zhenjiang), which sets off a chain of peculiar events. As A Rin covertly watches his new neighbor, Miss Li Xiao Jie (portrayed by Hu Yi Qi), playing a melody on her flute that he recognizes from long ago, he finds himself increasingly curious about her.
Simultaneously, A Rin learns of the unsolved case surrounding the disappearance of his mentor's wife, which seems to be linked to Miss Li Xiao Jie's sudden appearance. In the midst of this mystery, A Rin discovers a murder plot, landing himself in the crosshairs as the prime suspect.
As the story unfolds, we delve deeper into A Rin's hidden past, uncovering secrets that could shatter his life and the lives of many others. Will detective Li Ye Xin clear A Rin's name? Does every heart conceal a secret lock, and behind each door lie untold stories waiting to be revealed...?
