Leaving only a cryptic note, Andrew and Evie's mother vanishes on their eleventh birthday. Now, almost a year later, the twins receive a mysterious package from someone named Spy X. They soon learn that the contents of the box will lead them on an incredible journey toward finding their mother - and into a world where no one's identity can be trusted. In Book #1, Andrew and Evie aren't initially sure what to make of the package that arrives at their...

Twins Andrew and Evie search for their mother, a secret agent hiding from the Company, by solving the clues she has left for them in San Francisco, while trying to avoid the Company's agents, who hope the children will lead them to her.