On Halloween, ten-year-old Lucy is left home alone while her parents take her younger sister overseas. With the mind of a five-year-old, she clings to one promise: never open the door. When the power fails and she falls desperately ill, her parents dismiss her pleas for help. Outside, children knock for candy. Inside, Lucy keeps waiting. By the time her family returns, obedience has become a tragedy—and the truth behind her final night will haunt them forever.