The great thing about being 75 years old is that you can wear your slippers everywhere - Percy Sloggett wears his in the garden and to the shops as well as in the house. In time his battered old slippers need to be replaced and he gets something of a surprise when he discovers that his new pair are magic. They make him feel years younger and also make him strong and clever. Percy is desperate to tell someone his secret and so tells his friend's grand-daughter, Lollie - for of course children understand magic better than adults do. Percy's slippers turn out to be life-savers as they enable him to leap across the road to save Lollie from being knocked over by a car.