It's lady's maid Louisa Cannon's wedding day, but the fantasy is shattered shortly after when she is approached by a secretive man asking her to spy on Diana Mitford - who is having an affair with the infamous Oswald Mosley - and her similarly fascist sister Unity.
Thus as summer 1933 dawns, Louisa finds herself accompanying the Mitfords on a glitzy cruise, full of the starriest members of Society. But the waters run red when a man is found attacked, with suspects everywhere.
Back in London, the case is taken by lawyer Tom Mitford, and Louisa finds herself caught between worlds: of a love lost to blood, a family divided, and a country caught in conflict.
