The terrible and trecherous Pendragon plans to gain the throne of Cornwall by getting the king to abdicate and to marry his lovely daughter. To help him he has his dreadful witches in his castle and his almost unstoppable sorcery. A giant under his control abducts the princess, but on the way home with her the giant meets farming lad Jack who slays him. This is only the beginning.

When Emil travels by bus to Berlin to visit his grandmother and his cousin, his money is stolen by a crook who specializes in digging tunnels. Emil must get the money back as it is for his grandmother. While following the thief, Emil runs into Gustav, an enterprising young boy who gathers up all his friends to help Emil find the money. Emil's cousin also gets involved and they get into more trouble than they bargained for when Emil's pickpocket turns out to be mixed up with a couple of notorious bank robbers.