Aurelia Farnham is happy living in London's stylish Cavendish Square, but with her friends Livia and Cornelia both married, sometimes she longs for more. Then Colonel Sir Greville Falconer storms into her life, delivering a letter from her late husband, revealing he was a spy for the Colonel. The Colonel asks her to partner with him as he exposes a ring of Spanish spies who have infiltrated London society. When the simmering attraction between them ignites into passion and the danger of Aurelia's double life escalates, Aurelia realizes she has more than shadowy antagonists to fear.