11-year-old Lydia has run away from her wartime foster family to return home, only to find her seaside town abandoned and Grayfriar, her family home, desolate and empty. Heiden, a German soldier, arrives in the same night to occupy the house, and he imprisons the young girl there. Over five days, Heiden keeps Lydia hostage while turning the house upside down for official documents and other supplies--items, he explains, that will be useful for a pending German occupation. Over time, however, it becomes clear that there's more to Heiden's preparations than he is revealing, and more brought him to Grayfriar in particular than just his orders.