A pair of twins who travel across different worlds arrive in Teyvat, but attempt to leave after finding the nation of Khaenri’ah under cataclysmic siege. However, they are separated by a god who takes one twin and seals away the other. The sealed twin, referred to as the “Traveler”, awakens five hundred years later and meets Paimon, and the two embark on a journey to find the missing twin.
The duo first arrive in the city of Mondstadt, which has been under attack from a dragon called Stormterror. They meet with Venti, a local bard who wishes to calm Stormterror, who is actually Dvalin, one of the ancient protectors of Mondstadt. Retrieving a stolen holy lyre from the Fatui, Venti attempts to calm Dvalin down with the lyre, but the dragon is manipulated into attacking him by the Abyss Order. The encounter also reveals Venti to be the Anemo Archon Barbatos, and they pursue Dvalin and free him from the Abyss Order’s influence. After solving the crisis, Venti is ambushed by Fatui Harbinger La Signora, who steals his Gnosis, the symbol of an Archon’s power.
Venti advises the Traveler to travel to Liyue next to meet Rex Lapis, the Geo Archon at a ceremony. However, at the ceremony Rex Lapis is apparently killed, and his body is hidden away. Needing to escape suspicion, the Traveler gets help from funeral parlor consultant Zhongli and Fatui Harbinger Childe; the latter manipulates the Traveler into sowing conflict between the Qixing, the organization of trade heads who administer Liyue Harbor, and the Adepti, ancient guardians who defend Liyue. Childe discovers the location of Rex Lapis’ body, but is unable to find the Gnosis and believes Rex Lapis is still alive. To lure out the Archon, Childe resurrects an ancient god, but the combined forces of the Traveler, the Qixing, and the Adepti defeat it, after which the groups agree to usher Liyue into a new age. Afterwards, the Traveler discovers that Zhongli is Rex Lapis, who gives his Gnosis to Signora as part of a discreet contract with the Tsaritsa, the Cryo Archon and leader of the Fatui. Zhongli explains he faked his death so he could step down from his role as Archon, and their defense of Liyue proved they did not need his protection.
The Traveler then returns to Mondstadt and meets a man named Dainsleif who is targeting the Abyss Order. Together they investigate their plot to create an artificial god to topple Celestia, but as they attempt to thwart it, they are confronted by the Traveler’s sibling. They reveal themselves to be the leader of the Abyss Order, consisting of the people of Khaenri’ah cursed to become monsters, and reveal Dainsleif was a guard of Khaenri’ah cursed to wander the world. Dainsleif chases after their sibling but the Traveler is unable to follow.
While looking for a way into Inazuma, the Traveler learns more of the Vision Hunt Decree being enforced to confiscate the Visions of those in Inazuma, starting a civil war. Arriving in the nation, the Traveler agrees to help the resistance army abolish it. They learn that the Fatui manipulated the Shogun into signing it and raid a Fatui facility in response, but are defeated by Fatui Harbinger Scaramouche. They are saved by shrine maiden Yae Miko, who tells them that the “Raiden Shogun” is actually a puppet created by Ei to rule Inazuma while she retreated into her mind. The Traveler confronts Signora at the Shogun’s palace and challenges her to a duel and emerges victorious. Signora is executed by the Raiden Shogun, and the Traveler with help from Yae Miko defeat Ei, who repeals the decree, ending the war. Miko reveals that Ei’s Gnosis was entrusted to her, and that she relinquished it to Scaramouche in order to spare the Traveler.
The Traveler reunites with Dainsleif, who failed to find their twin. Seeing a vision of their sibling attempting to restore Khaenri’ah, they are torn between helping their sibling and defeating the Abyss Order. Dainsleif declares that the Traveler must choose before departing.