It’s the day of the great Pontypandy Canoe Race, and Ben and Hannah will be racing each other to the Harbour. Hannah is determined to win and sets off quickly, with Ben not far behind. Mandy and Norman meanwhile are distributing posters to ensure there will be a big crowd at the finish line to watch them cross the line. But Hannah and Ben don’t appear at the finish line when they should, and darkness is falling. Something is wrong - and Fireman Sam, Elvis and Penny are quickly on the case.