When Ibby is sent to stay with her Aunt, she discovers her cousin Francis, has shrunk to the size of a mouse using a magic set he found in the attic. Ibby is sure magic isn’t real but with her own eyes she can see Francis sitting at the bottom of the biscuit tin. Along with her other cousin Alex, the three children uncover the secrets contained in the box and try to solve the mystery of their Uncle’s disappearance.
