"Gravity Rush: The Animation - Overture" serves as a prequel to the events of the "Gravity Rush" video game series, bridging the narrative gap between the first and second games. The story centers on Kat, a young woman with the ability to manipulate gravity, who becomes the protector of Hekseville, a floating city besieged by mysterious creatures known as Nevi. After saving the city from a catastrophic event in the first game, Kat finds herself in a new predicament when a massive rift opens in the sky, threatening to engulf Hekseville. This rift, referred to as the "Boutoume," draws Kat into a parallel world where she encounters a young girl named Sachya, who possesses similar gravity-shifting abilities.

As Kat investigates the Boutoume, she learns that Sachya is being pursued by a shadowy organization seeking to exploit her powers. The narrative explores themes of identity and responsibility as Kat grapples with her role as a protector while uncovering the truth about Sachya's origins and the connection between their abilities. Alongside Kat is her loyal companion, Dusty, a mysterious cat-like creature who grants her gravity-shifting powers. The story also features recurring characters such as Raven, a fellow gravity shifter with a complex relationship to Kat, and Syd, a police officer who provides support and insight into the city's ongoing crises.

The plot delves into the consequences of Kat's actions in the first game, particularly the unintended fallout from her battle with the Nevi and the Boutoume's emergence. As Kat navigates the parallel world, she confronts new threats and uncovers secrets about the nature of gravity shifting and the origins of Hekseville. The animation maintains a focus on Kat's growth as a character, emphasizing her determination to protect others despite the personal risks involved. The story concludes with a setup for the events of "Gravity Rush 2," leaving key questions unanswered while establishing a foundation for the next chapter in the series.