UG, sad, happy or funny? The beginning is fun and enjoyable but later, Ug the stone-age boy, becomes sad and depressed. He's far too ahead of his time for anyone to understand him. He thinks up all kinds of inventions that are commonly used today, for example, fire so that the food could be cooked, wooden boats and light, soft balls for tennis and football. He even thinks of making a wheel. Ug also believes in feelings and affection, like giving his mother a bunch of flowers, just because they are pretty. Sadly for Ug, she mistakes them for food and eats them!
Ug is always having good ideas but all the other stone age people, like his parents Dug and Dugs and his friend Ag, think he's mad. When he grows out of his trousers, his ambition is to have a pair of soft trousers made out of the skin of a woolly mammoth rather than wearing stone trousers, but no one knows how to make them. Ug's dad tries to be helpful but Ug's idea are too advanced.
Ug's story makes us think about how we've developed from the stone age. Raymond Briggs's includes lots of jokes about how ideas may look silly to people at one time but often happen much later on.