Days 9 to 16 is the third 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 different parts of the US.

Finally realizing that she must leave the city, Elizabeth sets out alone along a deserted road. Eventually, however, she encounters some fellow survivors, and before long she's taken to a remote farmhouse where a small community is struggling to take shape. She soon discovers, however, that this particular farmhouse hides some dark secrets. Meanwhile, Thomas also encounters some other survivors, although he soon finds himself trapped in a battle for survival. Captured and held prisoner in a basement, he begins to realize that he might never find a way out.