1951. Brighton. With the excitement of the war over and the Nazis brought to justice at Nuremberg, Mirabelle Bevan (retired Secret Service) thinks her skills are no longer required. After the death of her lover she moves to the seaside to put the past behind her and takes a job as a secretary at a debt collection agency run by the charismatic Big Ben McGuigan. But when confronted by the case of Romana Laszlo, a pregnant Hungarian refugee, Mirabelle discovers that her specialist knowledge is vital. With enthusiastic assistance from the pretty insurance clerk down the corridor, Vesta Churchill, Mirabelle follows a mysterious trail of gold sovereigns, betting scams and corpses to a dark corner of Austerity Britain where the forces of evil remain alive and well.