Days 46 to 53 is the fourth 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.

More than a month after the disaster that crippled the world, Elizabeth and Toad are struggling to survive. Soon, however, Elizabeth faces a fresh problem, as she realizes that the virus might have claimed another, even younger victim. Meanwhile, Thomas discovers more survivors who are trying to reclaim the city. But is the mysterious Quinn really going to lead people to a new dawn, or is another act of unimaginable horror lurking right around the corner?