This companion to Life As We Knew It (2006) and The Dead and the Gone (2008, both Harcourt) brings together the teen protagonists of those books when Miranda Evans’s father and stepmother arrive with their new baby and a trio of strangers, including Alex Morales. For the past year, Miranda, her two brothers, and their mother have been living in the family home in Howell, PA, struggling to survive since an asteroid hit the Moon, destroying the Earth’s climate and causing millions to die. Deeply religious, Alex is determined to see his younger sister, Julie, safely to a convent before joining a monastery himself. When Miranda and Alex fall in love, she tries to persuade him to stay with her. Then a tornado hits Howell with tragic consequences, and Miranda must make a choice that may drive Alex away forever. As the narrator, Miranda dominates the book, but both she and Alex are sympathetic characters with her independence a nice complement to his sense of honor. Characters such as Miranda’s brothers, parents, and Julie play less of a role but are still likable and fully three-dimensional. It is a testament to the author’s skill that This World We Live In can be read as a stand-alone novel. In fact, new readers might not even realize that the earlier titles exist. Fans of Miranda and Alex, however, will keep this installment flying off the shelves, and the ambiguous ending will make them clamor for a fourth book.