Fourteen-year-old pickpocket John Jacob Turnstile has just been caught red-handed and is on his way to prison when an offer is put to him---a ship has been refitted over the last few months and is about to set sail with an important mission. The boy who was expected to serve as the captain's personal valet has been injured and a replacement must be found immediately. Given the choice of prison or a life at sea, John soon finds himself on board, meeting...