All of this started with a battle six thousand years ago, where the archangel Michael was defeated by a creature we now know as Thanatos. A creature who has, after millennia of waiting, taken hold of Michael.
They are hiding somewhere on Earth, gathering strength and waiting. Thousands of his Returner servants are moving across Europe, attacking any supernatural they find along the way. And now they have taken our parents, and we cannot save them on our own.