Hunted in Holland

On the way to visit his Dutch pen pal, Piet, Tim meets a tourist guide who turns out to be one of a gang smuggling stolen diamonds into Holland. Tim, Piet and his sister snatch the booty in Amsterdam and decide to try to reach Piet's brother who is a policeman in Rotterdam. By bicycle and barge, with the smugglers in hot pursuit, the children race through canals and cheese markets, among windmills and glass houses before reaching Rotterdam safely.