Zhou Fei, granddaughter of a national hero, is trapped in a secret fort once run by her family to protect the world from otherworldly warriors. Fed up with her isolated life, she tries to escape. Her fate changes when she nearly drowns and is saved by the free-spirited martial artist Xie Yun. Together, they form an unlikely bond and train to face new dangers, uncovering dark secrets along the way— including Xie Yun's true identity.