Everyone is so tired in the castle above the clouds that they fall asleep standing up. A whole week of thunderstorms every night means no one has had a wink of sleep. The little wizard Wobbletooth and his friends Princess Pustilla, Sir Turnip and Flutteric the dragon discover that the cause of all this is another dragon. The reason for his flashing and thundering is that he's sick. The four friends want to help him, so they embark on the difficult search for the mysterious cloudwort. This is the only medicine that can cure the dragon's stormy symptoms.