It's a bright afternoon in 1938 and Mary Foxe is in a confrontational mood. St John Fox, celebrated novelist, hasn't seen her in six years. He's unprepared for her afternoon visit, not least because she doesn't exist. He's infatuated with her - but he also made her up. 'You're a villain,' she tells him. 'A serial killer. can you grasp that?' Will Mr Fox meet his muse's challenge, to stop murdering his heroines and explore something of love? What will his wife Daphne think of this sudden change