In the early 20th century, the Yins and the Lus were two prominent families in Tangcheng. As time went on, the Lu family fell into decline, and internal strife broke out within the Yin family. To escape mounting debts, the Lu family's younger daughter, Lu Ye, faked her death and fled abroad, while the elder daughter, Lu Yi, married Yin Zhuofeng—the second son of the Yin family—to protect the Lus. Years later, Lu Yi dies unexpectedly. Lu Ye returns from overseas to attend her sister's funeral and reunites with her former brother-in-law, Yin Zhuofeng. In the process, she uncovers a web of connections between Lu Yi's death and a mysterious organization known as Yixin Society. Determined to seek justice, Lu Ye becomes Yin Zhuofeng's disciple and joins Bronze Leaf, an underground group he leads. She vows to become a blade of vengeance. As the two spend more time together, feelings quietly blossom between master and disciple, and a long-buried secret crush gradually comes to light. As truths about Lu Yi's identity and the intertwined history of the Yin and Lu families are revealed, the two begin to unravel the mystery behind Yixin Society. After surviving numerous life-and-death trials, Feng and Ye ultimately find love and embark on a shared path of justice.