A sixteen-year-old American traveling in Europe is shanghaied in an Italian port and forced aboard a crude schooner under a harsh captain. Separated from his father as war begins, he uses his sailing experience, physical resilience, and knowledge of languages to survive rough treatment, master shipboard tasks, and find a place among the crew. Episodes at sea emphasize improvised seamanship, courage under pressure, and solidarity with fellow sailors, while the vessel's missions draw the boy into broader naval operations against the enemy fleet, blending boyhood adventure with wartime patrol action.