It's the summer of 1965, and the Lee family has come thousands of miles to the naval base in Kodiak, Alaska. They're here to search for long-lost treasure, and in a show of goodwill, Mark's family is assigned to help them. But Mark's dad, Chief Allen, thinks the Lees are here for something else–to steal the Navy's top-secret weapon!
The Chief might be right, but Mark isn't so sure. And as he and Autumn become fast friends, Mark begins to wonder who the real spies are–and what they're up to. Why does the chaplain, Reverend Undyke, send secret signals at night? Is Lt. Grimes, the special agent from Washington, actually a Navy assassin stalking Mark and Autumn? And Miss Park, the Lee's creepy chaperone–whose side is she really on?
Despite their differences, the families grow close, and as they do Mark and Autumn realize it's up to them to protect the Navy's top secret–and also save the Lees from a terrible fate. Impossible, their parents think–but not for new friends with a super, secret plan!