Max and Martha Dalton live a carefree life of luxury and dinner parties in 1936 London, far removed from the increasingly brutal world. When an old army friend is murdered, however, Max finds himself drawn into the crime and back to his own past. With the slightly dubious help of Martha, their maid Flora, and a very confused solicitor, Max manages to uncover a plot that threatens the safety of the whole country. Meanwhile, Max is pursued by a police force that is convinced he's the murderer, and with unknown assassins hot on his trail.