Thomas is so excited to collect the brass band that he leaves the tuba player behind. The band leader realises this and Thomas looks for the tuba player. Meanwhile, the tuba player tries to fetch rides so he can head to Maithwaite.

'Arry and Bert tease Percy for only having a whistle. Percy becomes cross and practices whistling louder out of spite, not realising he's causing trouble for Thomas and Bertie. Percy later regrets it, but can't resist another whistle and whistles so loud that a giant snowball collides into him. However, the next day, he spots a snowdrift on the line, and hears Thomas approaching. Percy uses his whistle to save him and learns how to use a whistle properly.

Thomas is sent to work at the quarry with Mavis, though it turns out Diesel is there too. Diesel gives Thomas a hard time, declaring the Fat Controller is planning to scrap steam engines. The next morning, Salty brings fresh diesel fuel. Diesel boasts about it, but the fuel makes all of the diesels on the island sick.