Cathy and Jake are staying with their grandmother in Paddington in London during their summer holidays. A stranger comes to visit them. He calls himself a magician who, using his magic, turns Cathy into a Victorian looking girl with her brother in the form of a little dog by her side, all locked in a picture behind a picture frame. By the mysterious intervention of their grandmother the picture comes to hang on the wall in a doctor's home who is a psychiatrist. Apart from some patients, his visitors include the grandmother's friends who each play their part in unravelling and finally breaking the spell.