Tilly and George shrink in size with the striking of a magical grandfather clock. This time they meet up with and help a family of mice desperate to move from the house in which they have been living beneath the floorboards after a stray cat has taken up residency.

The children set off with the mice on an eventful journey. On the way they meet Bitz - a scary, hairy bluebottle, Sloop - a kindly water vole, plus a vindictive and temperamental frog, not to mention several other interesting creatures.

Their journey takes them along fast-flowing rivers, through windswept sand dunes, into captivity and finally freedom. Need I say more .......