Han Lei, a lieutenant and military doctor in the modern special forces, is driving a high-mobility ambulance along a rugged mountain road during a mission when a massive boulder triggers a landslide. The vehicle plunges over a cliff, landing in an ancient forest. Upon regaining consciousness, Han Lei witnesses a fierce battle between three men in ancient armor and dozens of pursuers wielding curved blades. One of the armored men, addressed as "Your Highness," is severely wounded. Han Lei instinctively draws her silenced pistol and eliminates several attackers, causing the pursuers to flee in terror. The wounded prince, Zhao Zun of Xiaoyao, and his two guards, Ping Chuan and Xiao Zhengfei, are left exhausted. Han Lei, initially confused and suspecting a film shoot, realizes the reality of the situation when she tests the prince's wound and confirms it is real blood. She learns she has traveled back in time to the Great Jing Dynasty.
The prince's guard, Ping Chuan, collapses due to poison from an arrow. Han Lei, disregarding her own disorientation, immediately performs emergency surgery inside the ambulance. She extracts the arrow, sutures the wound, and administers intravenous fluids and antidotes using her modern medical supplies. Her miraculous skills astonish the ancient guards. After saving Ping Chuan, she treats Zhao Zun's leg wound. During this process, Han Lei receives a "system" notification, rewarding her with gold for saving lives. She learns she is bound to this era and must complete tasks to earn resources.
Zhao Zun, recovering, explains the dire military situation. His garrison at Yong'an City is under siege by Tujue forces and is critically low on provisions due to a traitor among his guards who sabotaged their supply convoy. The Tujue army, led by Commander Alpi, had ambushed Zhao Zun's supply line, causing the provisions to fall into a ravine. Han Lei, now officially recruited as the camp's military doctor, uses her system to purchase ten thousand catties of grain and flour, delivering it to the starving soldiers. The sudden appearance of food boosts morale. Meanwhile, the Tujue forces, terrified by Han Lei's "peanut" bullets, retreat a hundred li, believing they faced overwhelming reinforcements.
Han Lei then turns her attention to the hundreds of wounded soldiers in the camp. Many have been deemed beyond saving by the elderly military doctors due to infection and neglect. Han Lei intervenes to stop a mercy killing, requesting twenty-four hours to treat them. She sets up a field hospital, teaching the soldiers proper wound cleaning with alcohol and distributing antibiotics. Working tirelessly through the night, she saves numerous lives, shocking the veteran doctors, including the initially skeptical Doctor He, who eventually begs to become her disciple. Her medical expertise and efficiency earn the respect of the troops and the deepening trust of Zhao Zun.
As the immediate crisis of food and wounded soldiers is resolved, Han Lei faces a new challenge: the system requires her to earn money for daily needs, as rewards are tied to good deeds. She purchases more grain and essential crops like sweet potatoes and salt, secretly storing them in a portable space dimension granted by the system. Zhao Zun, intrigued by her mysterious origins and capabilities, offers her a jade token granting her free access to his territory, signaling a growing alliance. The story concludes with Han Lei established as a key figure in the northern garrison, balancing her modern medical practice with the political and military complexities of the ancient dynasty, while the system continues to guide her actions through rewards and tasks tied to her interactions with Zhao Zun and the soldiers.
