* New York Times Bestseller
* Five starred reviews
* #1 Indie Next Pick
* ALA Notable Book

This thrilling WWII mysterya collaboration between award-winning and bestselling authors Ruta Sepetys and Steve Sheinkinis now in paperback!

Remember, you are bound by the Official Secrets Act

Summer, 1940. Nineteen-year-old Jakob Novis and his quirky younger sister, Lizzie, share a love of riddles and puzzles. And now theyre living inside of one. The quarrelsome siblings find themselves amid one of the greatest secrets of World War IIBritains eccentric codebreaking factory at Bletchley Park. As Jakob joins Bletchleys top minds to crack the Nazi’s Enigma cipher, fourteen-year-old Lizzie embarks on a mission to solve the mysterious disappearance of their mother.

The Battle of Britain rages and Hitlers invasion creeps closer. And at the same time, baffling messages and codes arrive on their doorstep while a menacing inspector lurks outside the gates of the Bletchley mansion. Are the messages truly for them, or are they a trap? Could the riddles of Enigma and their mother’s disappearance be somehow connected? Jakob and Lizzie must find a way to work together as they race to decipher clues that unravel a shocking puzzle that presents the ultimate challenge: How long must a secret be kept?