Clara and Robert Hatrell lead an ideal life with their young daughter Daisy in a beautiful old fashioned cottage on the banks of the Thames. When his son Cyril goes away to school their friend and neighbor Ambrose Arden who is a notable scholar offers to tutor Daisy. Some time later Robert carrying a large amount in banknotes is found stabbed to death in a London rooming house supposedly lured there by the mention of someone called Toinette. The murderer is not found and the money trail implicates a Frenchwoman exchanging the notes in Cannes, Nice and Paris. As the story progresses we are taken to Paris where new characters are introduced. Will one of them lead us to the actual villain ?