Sanny is an orphan, who was being raised her grandmother. The story begins in October, on Sanny's 7th birthday. Her grandmother has died. Sanny and her nurse, Maria, are leaving the small village of Cobblerrigg, Wensledale in Yorkshire to live with her great-uncle at Amberly Gardens, in Westminster in London. Sanny really believes in Santa, she thinks he's the nicest chap in the world and because there are so many toy shops in London, that where he must have his headquarters. However, when she discovers that Santa doesn't take wonderful gifts to her new friends Dick and Poppy and the other poor children of Buttercup court, she is determined to get to the bottom of the mystery. With the help of lady Mary and her Great Uncle she discovers the real meaning of Christmas and Santa Claus' Treasury.