When the Earl and his inventor friend Ruth host a Technology Fair at the castle, all sorts of amazing inventions find their way to Sodor, including Kenji - a brand-new electric engine said to be the fastest in the world! But as Thomas worries about the effect technology might have on his future, two sneaky thieves and their engine, Sonny - look to secure their own fortunes by making off with one of the marvellous inventions. It will be up to Thomas, Ruth, and the Steam Team to stop the thieves in their tracks!