Percy, a black and white pony called a piebald, is very sad as he has to leave his current stable and his friends. His owner, Mr Sands, was there when Percy was born. Percy is met at the new yard by Charlie and her faithfully St Bernard, Susie. But Percy does not like it there as it is all new and he does not know the other horses he will be living with. That night he sneaks out of the yard trying to find his old home. He meets his new owner, Penny Plum, a happy, excitable 10-year-old. She loves him from the very moment she sees him and wants to spend every moment of the day with him; she would even miss school. Penny is allowed to start riding Percy and she has never ridden before and she is so full of joy.

Together Percy and Penny, on their new journey, share an unbeatable friendship. Penny just wants to ride him all day, every day. Penny wants to look after him on her own. She is never disappointed as Percy loves her too. He will never ever run away again.