Lu Linzhao, leader of the Dark River gang, summons his younger brother Lu Ze, a mercenary, to eliminate a traitor within the organization. Lu Ze falls in love at first sight with Zhu Xia, a doctor, but a mistaken identity caused by the brothers switching identities leads to confusion. Through gang conflicts, kidnappings, and other twists and turns, they expose the insider and an overseas conspiracy. After Lu Ze reveals his true identity, he and Zhu Xia stay together, while Lu Linzhao unexpectedly becomes a doting father.