The game begins with Serge located in El Nido, a tropical archipelago inhabited by ancient natives, mainland colonists, and beings called Demi-humans. Serge slips into an alternate dimension in which he drowned on the beach ten years prior, and meets the thief, "Kid". As his adventure proceeds from here, Serge is able to recruit a multitude of allies to his cause. While assisting Kid in a heist at Viper Manor to steal the Frozen Flame, he learns that ten years before the present, the universe split into two dimensions—one in which Serge lived, and one in which he perished. Through Kid's Astral Amulet charm, Serge travels between the dimensions. At Fort Dragonia, with the use of a Dragonian artifact called the Dragon Tear, Lynx switches bodies with Serge. Unaware of the switch, Kid confides in Lynx, who stabs her as the real Serge helplessly watches. Lynx boasts of his victory and banishes Serge to a strange realm called the Temporal Vortex. He takes Kid under his wing, brainwashing her to believe the real Serge (in Lynx's body) is her enemy. Serge escapes with help from Harle, although his new body turns him into a stranger in his own world, with all the allies he had gained up to that point abandoning him due to his new appearance. Discovering that his new body prevents him from traveling across the dimensions, he sets out to regain his former body and learn more of the universal split that occurred ten years earlier, gaining a new band of allies along the way. He travels to a forbidden lagoon known as the Dead Sea—a wasteland frozen in time, dotted with futuristic ruins. At the center, he locates a man named Miguel and presumably "Home" world's Frozen Flame. Charged with guarding the Dead Sea by an entity named FATE, Miguel and three visions of Crono, Marle, and Lucca from "Chrono Trigger" explain that Serge's existence dooms "Home" world's future to destruction at the hands of Lavos. To prevent Serge from obtaining the Frozen Flame, FATE destroys the Dead Sea.