In 1898, an elderly widow, Anna Maria Druce, came to the British court with an astonishing request. She stood among the overflowing pews of St. Pauls Cathedral claiming that the merchant T. C. Druce, her late father-in-law, had in truth been a secret identity for none other than the deceased and enormously wealthy 5th Duke of Portland. Maintaining her composure amid growing agitation from the clutch of lawyers, journalists, and curious onlookers crowded into the church, Mrs. Druce claimed that Druce had been the duke's alter ego and that the duke had, in 1864, faked the death of his...