Jane appears to be ideal: attractive, intelligent, unruffled by her employer's abrupt eccentricities. But, gradually, we come aware that Jane has another agenda. Incrementally, Sir Paul's familiar surroundings are altered. His housekeeper is diverted away, strange things happen around the house and he becomes increasingly dependent on his new assistant.
Jane plays increasingly sadistic games until their relationship breaks down and it becomes clear that Jane intends to kill Sir Paul. Paul grasps this too late to save himself, but the plot carries further savage twists before it reaches its conclusion.