The film is a compilation of episodes 9‑13 from the 2017 television series. Riko and Reg descend into the third stratum, where Riko experiences the Curse for the first time. They then move deeper into the fourth layer; an Orbed Piercer injures Riko"s arm, prompting Reg to attempt a rescue. Nanachi arrives on the scene, healing Riko"s poisoned limb, and in return asks Reg to eliminate her immortal companion Mitty. Following this request, Nanachi joins Riko and Reg on their quest to reach the very bottom of the Abyss.
