During the Northern Wei Dynasty, the Rouran army invaded the border, and the country called up military residents to go out to battle. To perform the duty for her elderly father, Hua Mulan disguised herself as a man and came to Changpingcang. Originally, she just wanted to perform the duty for her father. Unexpectedly, in an action to save the prince, her friend Yuan Hong was captured and killed in front of her. From then on, Hua Mulan fought the enemy bravely and won many victories on the battlefield. When everybody was celebrating joyously, the enemy put millions of mice into the city, making the soldiers suffer heavily. For the prosperity of the country and the safety of people, Mulan and a few soldiers defended Changpingcang to the last at the cost of their lives.