Seven-year-old Wen and her parents, Eric and Andrew, are vacationing at a remote cabin on a quiet New Hampshire lake, with their closest neighbours more than two miles in either direction.As Wen catches grasshoppers in the front yard, a stranger unexpectedly appears in the driveway. Leonard is the largest man Wen has ever seen but he is young and friendly. Leonard and Wen talk and play until Leonard abruptly apologises and tells Wen, "None of what's going to happen is your fault". Three more strangers arrive at the cabin carrying unidentifiable, menacing objects. As Wen sprints inside to warn her parents, Leonard calls out, "Your dads won't want to let us in, Wen. But they have to. We need your help to save the world."So begins an unbearably tense, gripping tale of paranoia, sacrifice, apocalypse, and survival that escalates to a shattering conclusion, one in which the fate of a loving family and quite possibly all of humanity are intertwined.