Riki and Toby Are setting into their New lives on the Island of Berk Though they Still look very old-fashioned and could use new paint. Due to their bad paintwork the two become a subject of Scorn for Devious Diesel Who calls them "Dirty Object" Offended, Riki Asks why Diesel Is black and Diesel says then it is because he is splendid engine who is never dirty and ready for anything. Riki then teases Diesel by reminding him of The Bootlace incident, causing Diesel to become angry.
Later, at the end of the line, Diesel leaves his coaches and readies for his next train. He picks up a line of trucks for a slow good trains at each station. Diesel' mood is worsened due to the hate of slow good trains. Although the trucks start off behaving well, Diesel Is so rough with them that they end up being determined to pay him back as he starts to Climb up Obelix's Hill, Diesel is supposed to stop and have his brakes pinned down. Diesel who had an accident with trucks Before, should remember this, but forgets as he is too busy thinking of what he will say to Riki next time they meet. Seeing their chance, the trucks push Diesel down the hill. Unable to stop, Diesel runs through the station and crashes into a couple of Tar Tankers and derails.
Although Diesel is not badly hurt, he is covered from smoke box to cab in tar, while the tar tankers and some of the trucks are completely destroyed. James and Riki come to help clean up the mess and Riki makes fun of Diesel reminding him that, as a Black engine, he is supposed to look splendid and ready for anything. James And Riki take a sticky, dirty and rather very messy Diesel Back to Brave Tidmouth Shed where the Muscle Controller is waiting. He commends James And Riki for their hard work and sends Diesel to be cleared.
The Muscle Controller Awards Riki a new coat of paint and accepts Riki's Request that Toby and Henrietta have one as well. Riki happily run off to tell his coach the good news while Diesel remains silent, knowing full well that today he is the "dirty object."