After rescuing a kidnapped heiress and taking down a robot army, 11-year-old twins Nick and Tesla could really use a break. But before they can kick back and relax, the young sleuths discover there's a spy in their midst! Someone in the town of Half Moon Bay is spying on their Uncle Newt, an eccentric inventor. To uncover the true identity of this secret agent, Nick and Tesla must build their own spy gadgets, from burglar alarms and code wheels to a water balloon trap and more.