Allison gets a supernatural nemesis, wonderfully played by Mark Sheppard, who uses other people to commit vicious murders. It is a nice change of pace to see Allison face off against a proper nemesis who is a part of the supernatural world, which she deals with everyday.
Science fiction fans will know Mark Sheppard from great guest starring roles on the X-Files, Firefly and Chuck. He plays a great supernatural serial killer, and the writers did a good job of giving him a properly creepy background, which Allison has to slowly uncover. My only real complaint is that they should have had more episodes with this character in it, so that he could have been a true nemesis, instead of a villain who is only seen a few times, before being totally forgotten about.