On 21st April 1940 John the 9th Duke of Rutland, and one of Britain's wealthiest men, ended his days lying on a makeshift bed in a dank cramped suite in the servants' quarters of his home, Belvoir Castle, in Leicestershire.

After his death, his son and heir Charles, ordered that the rooms be locked up and they remained untouched for sixty years. But what lay behind this extraordinary set of circumstances?

For the first time, Catherine Bailey unravels a complex and compelling tale of love, honour and betrayal, played out in the grand salons of Britain's stately homes. At its core is a secret so dark that it consumed the life of the man who fought to his death to keep it hidden . . .