Having been rescued from the forest, Elizabeth is shocked to find herself living with a small group of survivors. But when she's plunged into an unlikely reunion, she begins to realize that the task of saving humanity might require difficult decisions.

Meanwhile, Thomas discovers the truth about another group of survivors. Old alliances are destroyed and new alliances are formed, but finally Thomas is forced to make a stand.

Days 54 to 61 is the fifth book in the Mass Extinction Event series, continuing the story of a worldwide apocalypse seen from the eyes of two very different people in two very different parts of the US.