One fine day, Dinny O'Shaughnessey spies the Leprechaun Finn, in the bushes mending shoes. With the help of his wife Katie and their sons, Dinny captures Finn, and sets about trying to win his gold. But a leprechaun's greatest defence is his riddle.

Katie, Dinny, and the five children set out on the highways and byways to find help in solving the puzzling riddle. Can they find the answer to the leprechaun's riddle in time? Will they find even greater treasures, right under their noses?