The city of Tokyo is under siege in 2027 by entities known as Lucifer Hawks from a world known as Nemesis. The Attacked Mystification Police (AMP) under Rally Cheyenne is dedicated to defending the city from them. New recruit Katsumi Liqueur wields formidable magic, but the Lucifer Hawks hunt her for their own purposes, led by a man named Ganossa Maximillian.

The TV series and movies are based on the manga by Kia Asamiya, published by Viz in the States. The manga is twelve volumes, and has also been published in the form of monthly comics. A prelude titled Mobius Klein covering Project Gaia also exists, but the English publisher Fanboy Entertainment went under after publishing only one comicbook volume.

The TV series diverges significantly from the manga, particularly in chronology and the timing of Lum Cheng\'s entrance. It ends roughly at vol. 11 of the manga, just before the final battle against Ganossa and the Lucifer Hawk. The first movie is based on vol. 5 of the manga, which covers Katsumi\'s first encounter with the Lucifer Hawk and Fuyuka\'s death as well as a later conflict with the Lucifer Hawk.