The Earl and his inventor friend Ruth are putting on a Technology Fair at the castle with inventions from around the world on display. Thomas becomes worried that he and the other steam engines will be replaced by new technology. To avoid this, Thomas tries desperately to make sure the Steam Team do their jobs as efficiently as possible. Unfortunately, he causes lots of confusion and delay instead. But Thomas soon feels better when Ruth tells him the steam engine is one of the best inventions ever. He then saves the day by heroically stopping an out of control rocket booster. After Ruth's pep talk and his daring rescue, Thomas is now confident that steam engines are irreplaceable... that is until a new arrival shows up at the Fair.