Whiff is extremely busy at his waste dump, so when Thomas tells him he's going to get another engine to help him out, he is very excited. Thomas puffs quickly to the Docks where Scruff "the Scruncher" was waiting for him. Thomas isn't very impressed; Scruff is small, square, and very scruffy. Thomas feels that a scruffy engine cannot be a really useful engine, so he tells Scruff that he is going to fetch a "welcome to Sodor surprise". Thomas collects a flatbed of buckets, sponges, soap suds, and a workman and takes them back to Scruff. It turns out that Scruff doesn't like his "surprise"; he had never seen soap suds and brushes before. They prove too scary for Scruff and he runs away! Thomas is shocked and chases after him.
After a short while, Scruff slips into an overgrown siding and hides. Thomas knows he's there, but he can't make Scruff come out. Then, Gordon arrives with the express. Thomas asks Gordon for help, so the big blue engine asks Scruff to come out of hiding to see the magnificent express carriages he's pulling. Scruff does not reply and Gordon steams away. Henry puffs up and Thomas asks him for help. Henry tries to entice Scruff out by offering to take him to see his special coal, but again Scruff is silent. Percy then arrives with his mail coaches. He offers to show the mail coaches to Scruff but, yet again, Scruff is not interested. Finally, Whiff arrives pulling a long line of rubbish trucks. He tells Thomas how excited he is to meet Scruff and then leaves. This gives Thomas an idea. He offers to take Scruff to collect some trucks of rubbish. Scruff is delighted and immediately comes out of hiding.
So, Thomas and Scruff set off to collect rubbish from the Steamworks, Knapford, and the Slate Quarry. They then take the rubbish trucks to Whiff's Waste Dump. Whiff is very impressed with Scruff's load and calls him a "Really Useful Engine".