Knapford Harbor is the harbor where ships drop off goods for trains to carry and passengers to travel on the express, hauled by Gordon or another engine.
Barry was shunting in the yard when James returned with a new injector and was to take a goods train out of the harbor. The trucks giggled and start to taunt him saying "Rusty, red scrap iron" twice at him. The black tender engine had enough of this and pushed them into the sea. He said that scrap is nothing to an engine and they should obey orders. James and Barry talked to each other about what happened and Diesel brought in the Breakdown Train to rescue them. Both the steam and diesel locomotives argued with each other about their past, including their own dates of withdrawal such as 1965 for Barry and 1967/1981 for Diesel. The controllers with Mike Western decided that he needs to be with Alice on her special train so that the black tender engine can speak to her about it and what happened at the harbor.