The guns of August are rumbling throughout Europe in the summer of 1914, but war has not yet touched Abingdon Pryory. Here, at the grand home of the Greville family, the parties, dances, and romances play on. Alexandra Greville embarks on her debutante season while brother Charles remains hopelessly in love with the beautiful, untitled Lydia Foxe, knowing that his father, the Earl of Stanmore, will never approve of the match. Downstairs the new servant, Ivy, struggles to adjust to the routines of the well-oiled household staff, as the arrival of American cousin Martin Rilke, a Chicago newspaperman, causes a stir.

But, ultimately, the Great War will not be denied, as what begins for the high-bred Grevilles as a glorious adventure soon takes its toll—shattering the household's tranquillity, crumbling class barriers, and bringing its myriad horrors home.