A tumultuous century dawns and two girls are born: one, a daughter of an English aristocrat; the other, the only child of a German cook. Harriet is privileged, wilful and impulsive. Emilie is polite, calm and studious. The two girls – so very different – become ‘forever sisters’ as they learn and play together in the peaceful Herefordshire countryside. But as the century grows older and they mature with it, events beyond their world profoundly change everything and everyone. War, hatred and fear sever their bond and tear them apart. Emilie reluctantly returns to the nation into which she was born but has never known; Harriet’s deep desire for purpose takes her to the horror of the Western Front.