Beinase, the sense of fear

Beinase says he comes from another realm. And we don't know if we can believe him. He spies, he pursuits, kidnaps, tortures... he meets dangerous people, sick people, living situations of pure horror, constant threat and violent atrocities. Is he mad? Is he a psycho? Or does he actually know something we ignore? Beinase's ear receives sounds that shouldn't get there. His eyes perceive images that don't belong to them. Each of his senses is being interfered. That is how he finds the clues to get to those dark characters he needs to reunite to fulfill his mission. But... what is his mission about?