

The engines are revved up for their homemade obstacle course event known as the Tri-and-a-half-a-lon. During practice, Nia worries that she's never been able to beat the timer, but Sandy and Carly encourage her to keep practicing before the event the next day.
On their way to a celebration for Thomas' 10,000th delivery, Percy tries to help Thomas with his big speech, but Thomas fails to listen. While distracted, Thomas doesn't notice when Percy falls off the track and gets lost. Percy tries unsuccessfully to find his way to familiar terrain.
When Bruno comes along to help Diesel get a heavy load to the Lighthouse, Bruno tries suggesting a safer route, but Diesel doesn't wait long enough to listen to him.