Wet Magic

And when that mermaid is captured and put on display at a local circus they decide they must rescue her. As their reward they are permitted to visit the hidden kingdom of the mer-people but find they must now stop a war to save their new friends. That going to the seaside was the very beginning of everything - only it seemed as though it were going to be a beginning without an end like the roads on the Sussex downs which look like roads and then look like paths and then turn into sheep-tracks and then are just grass and furze bushes and tottergrass and harebells and rabbits and chalk.