Long running Children's TV series telling the stories and adventures of a young schoolboy who gains the power of transforming himself into a dog. Only his best friend knows this and helps him protect the secret from the boy's parents, the school headmaster Mr. Blocker and also from their friend and their school-teacher Miss Jessop. Over the years, the cast changes (due to the young children growing up.) so that we see three different set of adventures for three school-children (with always a boy the one who turns into a dog.) with three different breeds of dog - all with Miss Jessop linking them... Written by Lee Horton