In 2027, the Great Xia Flame Dragon Special Operations Team accidentally travels through time to the war-torn Great Song Dynasty while pursuing an alien monster. At this moment, the Northern Yuan Great Khan, Temuge, arrives at Sanjiang City with 100,000 cavalrymen. The people are brutally slaughtered, and the dynasty teeters on the brink of collapse. Team leader Fang Ziming resolutely leads his four teammates into battle, using modern firearms, drones, robotic military dogs, and advanced tactics to repeatedly defeat the Northern Yuan army. Facing enemy sieges, food and supply shortages, and political intrigues at court, the five join forces with the Great Song defenders to fight fiercely. With the power of modern special forces, they turn the tide of an ancient war, vowing to defend Sanjiang City to the death and write a legendary tale of courage spanning time and space.