Percy's Squeak! is a read-and-colour magazine story.
Percy hardly ever needs repairing and is always ready for work. But one day, Percy hears a peculiar squeaking noise whilst shunting trucks in the yard. The trucks tease him, telling him that he sounds like a mouse. Percy feels very embarrassed. Eventually the Fat Controller asks the maintenance staff to have a look at Percy. They oil Percy, but find nothing wrong with him and the troublesome squeaking remains with him.
That night, Percy and the other engines try to go to sleep, but his squeaking keeps everyone awake. Percy is still squeaking in the morning when his driver arrives. The Fat Controller tells Percy not to work until the squeaking noise goes away and the driver and fireman agree to give Percy one final check. At last the fireman opens the boiler and the squeaking noise became louder. The fireman starts laughing, then the driver goes to look and starts laughing too. The driver and fireman then hold up four tiny mice. The trucks had been right and all of the engines laugh, even Percy.
- The plot is similar and may have even been the basis for the sixth season episode, Thomas, Percy and the Squeak.