The Order of Magdalene is a religious, militaristic organization of the catholic church dedicated to exterminating all sorts of monsters and investigating mysterious supernatural cases in the United States of America. The Order has many branches around the country, some that are mentioned or visited include the San Francisco and Seattle branches, but some of the most influential ones are in New York and Chicago. The Order also has the duty of protecting people blessed with special abilities, like the Apostles, from any evil person who desires to use their powers for their own ambitious purposes; each one is presided over by the Council of the Catholic Church. The Order of Magdalene is also a powerful, technologically advanced organization, and its members have to undergo very difficult military training and are sent to all kinds of dangerous missions. Although most of the members are humble servants of God, in times of great crisis, other less generally accepted individuals may be introduced into the Order to help fight the forces of darkness, an example of this being Chrono, a Demon, and Rosette, a person who make a contract with a Demon. Both are out of place in a organization like the Order of Magdalene.

The Order use various weapons, mainly guns, swords, and melee weapons, many of which are developed by the New York branch's own Edward Hamilton. The Order's preferred handgun is the Colt 1911, often loaded with Sacred. Besides using guns, there are members of the Order with special powers as well, using devices like tomes, violins, or dolls. They also use Angel Capture Fields, specialized barriers that can repel Demons, their powers, and other Astral based substances, and are set up by creating a rectangular array of cross-shaped stakes in the ground and activating them.