mysterious incident that hints at sabotage. The opening of the book introduces the boys aboard the transport ship as they leave Brest, France, filled with excitement for their return home. Amid the hustle and bustle on deck, humor is shared between the characters, but tension soon brews when the ship unexpectedly turns back toward port due to a reported malfunction. As confusion ripples through the vessel, Jerry attributes it to potential sabotage linked to a suspicious little man, known as "le cochon," whom they've encountered before. The suspense escalates with an explosion in the engine room, leading to their ship being disabled at sea, and casting the boys into a web of mystery as they prepare for the next developments in their gripping adventure. (This is an automatically generated summary.)