A murder has occurred at the country home of Sir Daniel and Lady Barbara Penwarden, and the prime suspect is the new tutor to the couple's daughter. A murder mystery with many twists and turns and dark family secrets to keep the armchair sleuth guessing.

Avon Eve, a successful writer for films and television, checks into a spa for a week of rest and relaxation. There, she is assigned a masseuse, Sonja, who the director of the spa calls the Smiler for her constantly pleasant and smiling disposition. Sonia has heard of Avon and is particularly enchanted by one of her works for television - one that Avon thinks is quite dreadful. As they spend more time together, Sonja begins to remember a failed love affair with Sir Jonathan Sibley who claimed to have loved her but refused to marry. When her old love arrives at the spa with his wife - and fails to even recognize Sonja - she becomes unhinged and plays a terrifying game of Russian roulette.