After resigning, working stiff Lu Wei moves into a remote cave dwelling, getting to know the time-traveling Prince Huo Qing, who guards the northern desert border. Huo Qing leads 100,000 cavalry in a sneak attack against 800,000 Wojnu, but suffers betrayal and an ambush leak, leading to failure. Only over a hundred men escape into the eerie Mangdang Mountains, where the Wojnu besiege them with 300,000 troops. Lu Wei provides him with supplies, drones, and other modern equipment, helping him rescue the Huo family members being led to the execution ground. Later, she also provides Huo Qing with heavy crossbows, stun batons, snowmobiles, and ten secondhand copies of The Art of War, etc. Huo Qing wins battle after battle, repelling the Wojnu cavalry with carts and firecrackers, and ultimately successfully escapes, roots out the traitor, and clears the name to avenge the fallen cavalry.