The woman here is Sylvia Russell: power mad with set goals. In order to achieve those goals she is sadistically devoted to her son and daughter, able to possess and direct them. She subtly ruins her daughter's marriage by corrupting a servant girl and, then, uses her to compromise her son-in-law; slowly breaks her bumbling, unambitious husband's confidence...

After leaving the British Secret Service, David Somers finds work catalouging butterflies at the country house of Nicholas and Jess Fenton. After the murder of a local gamekeeper, suspicion falls on their niece, Sophie Malraux. Somers helps Sophie to escape arrest and they go on the run together.