It's been a month since the bombing of Pearl Harbor. America is officially at war with Germany and Japan, and everyone wants to do their part. In twelve-year-old Colton's case, that means stepping up at home once his older brother, Danny, ships out with the navy. But before Danny leaves for boot camp, the brothers are fishing on the Atlantic Ocean when Danny's boat is capsized by a Nazi U-boat, nearly killing him.

When more U-boats start attacking the next day, Colton realizes just how close the enemy is to American shores. With Danny's life in the balance, Colton does the only thing he can think of to help his family and his country: He steals his brother's enlisting papers and joins up instead.

Colton's bold decision leads to a deadly journey. Even if he can keep his age a secret and survive boot camp, he'll have to face Hitler's ruthless submarines. But the longer he's on the seas, the less sure sure Colton is that he and his shipmates can stop such a relentless enemy . . .