The movie is based on Yukito Kishiro's manga Gunnm, also known as Battle Angel Alita.
It follows the story of the titular Alita, a disembodied "core" who awakens with no memory in a post-apocalyptic world destroyed by a technological fall. Dr. Ido finds her and gives her a new body. They later discover that Alita is more than what she seems and has an extraordinary past. As she navigates her new life, she battles other machines who are empowered with skills.