Maddie's life is a mess. Along with the usual hassles of eighth grade, her best friend Rachel has gone boy-crazy and seems drawn to a new crowd. To make matters worse, everyone's teasing Maddie for impulsively breaking into her neighbor's home when her imagination went wild thinking that she saw a mythical creature called a Yeti inside.

Then, the new neighbors pull into their driveway and Maddie thinks she sees a human hand push out the taillight of their car. Other strange events follow. Are they kidnappers? Spies? Maddie convinces Rachel to help investigate, hoping that working together will bolster their friendship. But that looks unlikely after both of them crush on the new neighbors' son Alex.

Maddie is in a no-win situation. If she proves the new neighbors are spies, Alex will hate her. If she finds out they're not spies and dates Alex, Rachel will hate her. But Maddie can't resist solving a mystery and soon finds herself on a collision course with her best friend, her first crush, and the dangerous world of espionage. Her entire world - and her life - is at risk.