It's former 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. Another timeless whodunnit with the fascinating Mitford sisters at its heart.