Shen Yanqiu, a poor boy from the Wudang Mountains, was taken under the sect of the master Xuanxu because of his talent. However, he was eager to become stronger and used the sword fiercely, which was incompatible with the Wudang Tai Chi Sword's concept of "conquering strength with softness". With his obsession to let his mother live a good life, he hoped to be promoted to the inner sect in the Sword Discussion Conference, but he did not know that he had fallen into the conspiracy trap of the inner sect disciple Wu Changfeng.
On Siguo Cliff, he was lured into learning the evil sect's "The Heartless Sword Manual"; at the head's birthday party, he was falsely accused of betraying the master, and Xuanxu cut off his right arm regardless of the reason and was expelled from the master. Shen Yanqiu, who fell into a desperate situation, met Mo Chen, a former Wudang disciple who had lived in seclusion for thirty years by a cold pond. He learned the inheritance of the "One-Armed Sword Sutra" and practiced swordsmanship with one arm, resurrecting himself in the desperate situation.
Afterwards, he sought his mother and broke into the Black Wind Stronghold, fought poisonous pythons, beheaded the leader of the stronghold, and regained his strength amidst the light and shadow of swords. When he heard that Wudang was invaded by the remnant forces of the Nether Sect and Wu Changfeng, and Li Muran was imprisoned, he resolutely returned to Wudang, using his one-armed sword power to break through dungeons, kill evil spirits, and put an end to the rebellion.
From a spirited young man to a one-armed sword demon, Shen Yanqiu struggled with hatred and protection, and grew up amidst the disputes in the world and the grudges of the sect. In the end, he put aside the turmoil in the world, returned to the valley with his mother, and buried the green steel sword under the peach, leaving only a legend of the "Wudang Sword Demon" quietly spreading in the martial arts world. The story uses fierce martial arts fights and the ups and downs of the characters' fates to outline a legend about revenge, redemption and letting go.
