Dark Corners by Ruth Rendell

Carl Martin has inherited a house from his father in a very desirable area of London. As a novelist, he needs a bit of extra income, so decides to rent out part of the home. At first, things go well with tenant Dermot McKinnon--but when Dermot starts to blackmail him, Carl finds himself in a terrible bind that affects both his work and his relationship with his girlfriend, Nicola. Carl's life then starts to unravel in ways he could not possibly imagine... Dark Corners will be published in October.