At the docks, Cranky has carelessly dropped a load of fish onto Thomas. At last, all the boxes of fish are loaded and Thomas sets off. He loves steaming along beside the sea. Thomas has not gone very far when a signalman flags him down. The signalman informs Thomas' crew that the track ahead had been damaged by waves. Thomas' driver promises the signalman that they will warn the other engines.
It gets dark as Thomas chuffs into the big station. Henry is complaining about Thomas being late. Thomas tells the big engine how difficult and dangerous his journey had been. Henry steams off along the seaside track, determined to show Thomas how fast he can get to the harbour. It was now very dark and foggy and the signalman had gone home. The next minute, Henry felt the tracks crack beneath his wheels and he slid into the sea.
Henry has to wait until morning to be rescued. A crane lifts him into a barge filled with smelly fish. The children and Cranky laugh as Henry is towed back. When Cranky finally stops laughing, he lifts Henry back onto the rails. The Fat Controller then orders Thomas to pull Henry to the wash-down, so that he can be cleaned before he returns to work.