PJ and the Paranormal Pursuers. The Mackenzie Poltergeist, Paperback/Jacqui Dempster

After his mom dies, PJ reluctantly leaves his New York home and everyone he loves, to live with his Aunt Katie in Edinburgh. A series of strange events begin when his aunt's elderly neighbour and her cat Azrael convince him that his mom, weirdly, is still very much with him.