Part 6 of 6 and final part of the children's drama from 1991. When Billy shows Trevor Trotman the mysterious book he found in his bag, "Ringing the Changes", Trevor suddenly realizes what is going on. He tells Billy that in the book is a character who could change into anybody just by wearing a magical ring and it is his belief that the character has escaped from the book and is causing all the mischief for Billy. The only way of stopping him is to try and trap him - but how can you trap someone who can look like anybody?
