While Kana and Thomas deliver aquarium materials for the Vicarstown Fish Day, it's up to steady Percy and Nia to deliver the fish themselves. However, Nia gets a wobbly wheel, inciting Percy to ask Kana for a switch so she can help Nia and speed up the delivery. Once Nia is fixed, she's raring to go, but Kana unexpectedly wants to slow things down to keep the fish safe. Could this quarrel spell doom for the delivery or allow these engines to learn something they never realized about each other?

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. When Diesel barrels though Crumble Canyon, Bruno must brake hard to keep them safe. The squeal causes a rock avalanche and blocks them in. Diesel learns to open his ears to collaborate with Bruno on a solution that uses both their strengths to get out.

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. Thomas realizes he wasn't listening to Percy after all! He abandons his delivery ceremony to find Percy! Thomas uses what he knows about his best friend to track him down, proving how well he knows his loc-amigo.