Lady Violet Hughes is keeping secrets. First, she founded London's first social club for ladies to provide sanctuary for England's most brilliant female scientists. Second, she is using her genius on a clandestine mission for the Crown. But the biggest secret of all? Her feelings for protection officer Arthur Kneland. When a shadowy threat infiltrates Violet's laboratories, scientist and bodyguard will find all their theories put to the test - and learn that the most important discoveries are those of the heart.