In the process of writing a new novel. 10% completed. A real twist on subject of posession.

Alistair Green lived in London England, 1937. He owned a small used bookshop. After reading a hand written manuscript, something strange happened to him. He felt something  enter his body just after he is finished reading the papers signed by, none other than, Jack The Ripper. Could the writer actually have been who he claimed to be? What  happened to Alistair? Where did this all lead to?