Young Killian Melville is arguably the most brilliant architect of the age; passionate about his art, he is liked by everyone. So when he visits Sir Oliver Rathbone, in need of a lawyer to represent him over his alleged 'breach of promise' to marry the daughter of his patron, Rathbone agrees despite his misgvings.

The case is not an easy one. Zillah is beautiful and even-tempered, heiress to a fortune and a good friend. What more could any man want? And why would Melville risk losing the professional reputation he has worked all his life to build?

Frustrated by his client's refusal to divulge any further information, and convined he is keeping something from him, Rathbone, his own professional integrity at stake, decides to ask his close friend Hester Latterly for an objective opinion about the case. She, meanwhile, has contacted William Monk to investigate a mysterious family matter from twenty years ago. Little do they realise that the three of them are about to tackle the most baffling and complex case with which they have ever been faced...