Sophie Foster is a fugitive – but at least she's not alone. Her best friends from the Lost Cities have followed her to join the Black Swan. They still have doubts about the secret organization, but the only way to find answers is to work with them. And as they adjust to their new life, they discover secrets far greater than they ever imagined. But the enemies strike again, unleashing a terrifying epidemic that threatens the safety of an entire species. Sophie and her friends fight with all their might – and with the help of new allies who follow them – but every choice has its consequences. And trusting the wrong person can bring death. In this thrilling fourth book of the series, Sophie must question everything to discover the truth that will either save the world or destroy it. • The series already numbers 9 books, has sold more than 3.7 million copies worldwide, and has been awarded the California Young Reader Medal Award. • A film adaptation is being prepared by Disney, directed by Ben Affleck. • On the bestseller list of the New York Times, USA TODAY, Publishers Weekly, and Wall Street Journal.