When Arnold Clover is recruited by Lizzie Hawker to help her look into her family inheritance, he cannot begin to guess the journey he is about to embark on.

Lizzie's mother, an Italian countess, disappeared thirty years ago, presumed dead. Her father, a famous, some say infamous, music promoter, has just died and now the family home Ca' Scacchi, a leaning palazzo in Dorsoduro, has fallen to her. When her mother vanished so too did a priceless painting, supposedly an erotic portrait of Lucrezia Borgia, which has captivated men for generations.

When a body is discovered in a hidden crypt beneath the checkerboard courtyard of the palazzo, other secrets are unearthed with it. Lying with the body is a document, a story of an episode in Casanova's colourful life, and within it a set of clues that might lead to the location of the painting. But it quickly becomes apparent that Lizzie and Arnold are not the only ones interested in finding the painting.

The search for the lost Lucrezia quickly becomes a race through the secret history of Venice, one with potentially deadly consequences.