In 1905, John Vanbrugh, an ambitious, young architect, receives an invitation from the Duchess of Marlborough, the American-born Consuelo Vanderbilt, to visit Blenheim Palace and help her with renovations. And so young Vanbrugh joins a weekend house party which includes a young Winston Churchill and John Singer Sargent, who has been hired to paint a family portrait. Right away Vanbrugh learns that Blenheim has many dark secrets. The mystery grows larger as a young housemaid is found strangled in the courtyard. From there, events spin out of control, with Vanbrugh soon realising that he too has fallen victim to the cursed history of Blenheim.