While High Meadow is dealing with troublemakers and raiders, Wisp follows an invisible trail across the country to rescue Nick.
What had started as a simple trip turns into an undercover operation for Nick, leaving Wisp to return to High Meadow on his own with a van full of children. In the search for answers, Nick learns that the problems are more complex than he imagined. The country's minimal infrastructure is teetering on the brink of collapse. And the people in charge are not at all what he'd hoped.
Angus predicts that the high mortality rate from the last round of flu could cause the disintegration of smaller settlements putting people on the road. With the train stations closed, there will be no food or shelter for these refugees, leaving them victim to marauders and starvation.
As Tillie scrambles to plan for a winter without train food, the influx of refugees is eating up precious supplies.
The world is changing again and they must adapt or die.