When Cammie Morgan enrolled at the Gallagher Academy, she knew she was preparing for the dangerous life of a spy. What she didn't realize was that she would have to face off against an ancient terrorist organization dead set on kidnapping her during her junior year. When a terrifying encounter in London reveals that one of her most-trusted allies is actually a rogue double-agent, Cammie no longer knows if she can trust her classmates, her teachers-or even her own heart.

Now the Gallagher Girls must hack, spy, steal, and lie their way to the truth as they discover that the key to Cammie's future may lie deep in the past.