Il Ghostwriter - The Ghost, by Robert Harris (2007, UK)

Adam Lang is the ex premier of UK, now in USA with his wife Ruth. He's writing down his life, helped by Mike McAra... who misteryously dies. The narrator is a young professional ghostwriter, asked to continue the job... in a strange high level alert climate. Is CIA involved? Strange deaths happen. Regardless himself, he finds out himself trying and solve the mystery. The genius is in the end.