The adventures of the beautiful, enigmatic and always surprising Dr. Helen Magnus, a brilliant scientist who holds the secrets of a clandestine population called Abnormals - a group of strange and sometimes terrifying beings that hide among humans. Magnus seeks to protect this threatened phenomena as well as unlock the mysteries behind their existence.
Hel receives an invitation to visit her estranged twin Siri at an exclusive residential sanatorium set against the idyllic setting of the Italian Alps. Tension soon rises when Hel refuses Siri’s plea for help in taking care of some business by swapping places with her for a few days. Much to her horror, Hel wakes up the next day to find Siri gone. She soon realizes that Siri isn’t coming back, and that the clinic is far from a place of recovery.
Setsuna, a High School student, not only has to deal with bullies and more then appropiate feelings for his own sister, but also must come to terms with the fact that he is the reincarnation of the Organic Angel Alexiel who rebelled against God. Being thrust into a world he never knew existed he must believe that angels and demons exist for the sake of Heaven, Earth and even Hell.