The new Mayoress, accompanied by her nephew Denzil, is touring Chuggington. She's observing the chuggers working, in order to help her decide who should be the recipient of the prestigious Chugger of the Year award. Koko is sure she's in with a chance - but rather than doing her jobs, she spends her time trying to impress the Mayoress. In the process, she ends up nearly ruining the ceremony.