Blood Shadow, a top assassin, becomes the target of the Shadow organization after her exceptional abilities arouse its fear. Following a laboratory explosion, her soul is reborn in the body of Qiao Ying, an 18-year-old girl in Yuncheng who weighs 200 jin (100 kg) and is constantly bullied. No longer timid, she fights back fiercely. Thanks to her outstanding mathematical talent, she earns a recommendation to Jing University and receives a million-yuan reward for saving Qin Yuchen. After arriving in the capital, she navigates the Qin family while revealing her extraordinary hacking skills, medical expertise, and formidable combat abilities. She travels to M Continent to compete in the Fighting Arena and rebuild the Blackwater Mercenary Corps. Back at Jing University, she handles her classmates' provocations while navigating rival factions. As she investigates the conspiracy of Wei Qingyuan, the Shadow organization's third-in-command known as King of Hearts K, she unravels the deadly Blue Begonia poison to save Qin Hanyue's father and confronts Shadow assassins. Amid a battle of competing forces, she plans every move carefully and waits for the perfect opportunity to exact her revenge.