In this third book in the American Revolutionary War Adventures series, John and Ambrose Clark are hot on the trail of the spy who gave away the secret of their fathers mission, which ultimately led to him being shot by Redcoats. But when there is an attack on Americas new strategic defense on the Hudson Riverthe Great Chain at West Pointthe twins must protect it. They soon discover things arent always as they seem and their friends have deadly connections....

Fifteen-year-old twins John and Ambrose man one of the first submarines in order to transport gunpowder to the patriots and then attempt a prison break to rescue one of their older brothers.