Locksmith Li Tao gets cheated out of a 50-yuan service fee by Wang Cuifen, an older woman. After standing up for himself, he becomes the target of a series of retaliatory attacks by her son, Zhang Qiang. From extortion and theft to the destruction of his tools, kidnapping, and assault, Zhang Qiang and his mother relentlessly push him into one dangerous situation after another. Relying on his exceptional locksmithing skills and strong sense of justice, Li Tao repeatedly outsmarts them. After rescuing Su Wanqing's niece, he is recruited by Shengshi Group. He later saves Elder Chen, earning the admiration of powerful figures. In the end, Zhang Qiang escapes from prison and kidnaps someone, but is sentenced to death. The Zhou family's attempt to forcibly demolish a nursing home is completely crushed. Rising from an ordinary locksmith to Head of Security and Vice President of the company, Li Tao marries Su Wanqing, and the family finally reunites in happiness.