The angel of Polh

Emily, an angel of Polh, arrives in Chicago to find the murderer of a person for whom she was responsible. But the culprit is a vampire and the angel, young and inexperienced, can't lay hands on him. Then, she gets into her head to seek help from Ladainian Abernaker, the most unlikely ally. The cantankerous old man would certainly never listen to her request without the unfortunate intervention of the leader of the vampires of Chicago.