Xiao Tianluo, a legendary soldier king, transmigrates into the body of an orphan in Great Chu. To raise money for the imperial military examination, he applies for a position as a guard at the Marquis of Xuanwu's residence. Unexpectedly, he ends up sleeping with Zhu Jiu'er, the seemingly frail eldest daughter, and is forced to marry into her family under a three-year agreement allowing him to leave afterward. After their marriage, he discovers that Zhu Jiu'er is strong beneath her delicate exterior and has secretly been investigating the mystery surrounding her parents' disappearance. Using his modern knowledge, Xiao Tianluo invents soap and scented soap, saves the marquis's declining businesses, exposes corruption at an estate, and foils a prince's conspiracy. However, he unexpectedly discovers that Zhu Jiu'er herself was behind the events that brought them together, having chosen him to escape a royal arranged marriage. Faced with deception and a crisis threatening the marquis's household, Xiao Tianluo decides to join forces with her to stand against imperial power.