In the Western Zhou, at the foot of Mount Tianzhu, the Jiwu Village clans of Hu Long and Ying raise dragon colts together. The place is known as the Hometown of Cavalry.
The Ying clan's young Yang and Run of the Hu Long clan train in martial arts together from childhood. Run hatches a Azure Dragon and helps it shed its skin with his own blood. But when Hua'er, a young woman from the neighboring Huaxu clan, visits her uncle in Jiwu Village, she becomes the Azure Dragon's fated master. Bound by their pact, Hua'er is chosen by the mortal enemies of her clan, the Jiuli, to be their crown prince's consort.
Yang's father, Congxi, and Run's father, Muyun, lead an expedition against the Western Rong. When the Duke of Qin proposes a marriage alliance with the Western Rong, Congxi strongly objects and is imprisoned. Yang flees.
In Mei, Yang is attacked by wolves and rescued by an old man. Later, in Mei's bustling market, Yang saves Mu'er, who is disguised as a man.
The Jiuli crown prince comes to Mei to invite the old man to serve as regent in Jiuli and reform its savage ways. The old man agrees, but Mu'er vanishes on the eve of his departure.
On their way through Dasan Pass, a mountain spirit is devouring people. A sorcerer posing as Mr. Mo Ling, the Grand Priest of Chu, is eaten too, but Yang slays the spirit. The Pass Commander asks the two for help solving the mystery of the Ying Qin nobles who have gone missing, and Yang discovers Muyun's weapon.
At Jianmen Pass, they meet Muyun. They learn that the Duke of Qin is making a southern tour and that the state of Ba plans to kill him. Ba's forces besiege Jianmen Pass. Muyun summons a red dragon, and Yang and the newly arrived Run join forces to attack. They capture the ruler of Ba alive, and Ba and Shu make peace.
In Chengdu, Yang reunites with Mu'er. She is the Duke of Qin's younger sister. Unwilling to marry into the Western Rong, she fled from Qianyi. The Duke of Qin found her during his southern tour, and they traveled together to Chengdu to attend the Son of Heaven's chariot-racing contest.
Yang and Run enter the contest. Run wins the gold medal and is selected for the Son of Heaven's personal chariot guard. Yang, however, destroys his chariot while saving Jiu Fanggao.
Run goes to Haojing for service.
Yang and Mu'er travel south with the old man. He subdues the murderous Blue Ox with Branched Horns, only to discover the Jiuli crown prince's shocking plot...
