All Mike Danford wants to do is build his own submarine. It's a big job for a teenager, but with his best friend Josh he's making it happen. But somebody is trying to stop them. Mike is sure he knows who it is, but no one will believe him. As the boys defend themselves against constant sneak attacks, they launch the sub -- and launch themselves into events that threaten their lives! Only with the help of Mike's dad, the Navy, and God's grace can the two survive . . .