Theo is good at most things. He can almost count to a thousand, knows several French words and can operate the washing machine. But he can't lie or steal. “You must try harder,” says his mother sternly. The Pincher family love to steal things. It’s what they are born for! When his parents leave to visit the diamond exhibition, Theo's heart sinks. After breaking Grandma out of prison (his little sister needs someone to read her bedtime story), Theo sees no alternative but to stop his parents stealing the diamond. His shout of “Stop! Police!” brings them only delight - Theo's lie has shown he is a true Pincher.