It's the summer of 1939, and after touring an unsettled Europe to promote her latest book, Romily Temple returns home to Island House and the love of her life, the charismatic Jack Devereux. But when Jack falls ill, his estranged family are called home and given seven days to find a way to bury their resentments and come together. With war now declared, each member of the family is reluctantly forced to accept their new stepmother and confront their own shortcomings. But can the habits of a lifetime be changed in one week? And can Romily, a woman who thrives on adventure, cope with the life that has been so unexpectedly thrust upon her?