Li Weijun, a modern young man, traveled through time and became an orphan of the Dayin Dynasty. He was bullied by the village chief who seized his land. In order to survive, he beat the Dengwen drum and unexpectedly met Emperor Yin and Princess Fengyang Li Ruowan. After joining the Secret Patrol Division, he wisely solved Cui Hongzhi's wife murder case, suppressed prominent families, and solved the granary crisis. During the struggle, he gradually uncovered the mystery of his life experience, developed feelings for the princess, and eventually helped stabilize the court and win respect and love.
