The Engines are celebrating May Day. Knapford Station is being decorated and Richard Hatt agrees to let the engines be decorated, but Marie states that decorations are undignified for an important engine like her and puffs away.
At Tidmouth Sheds, everyone is being decorated. Percy has flags and streamers, Thomas has big red banners and Murdoch is being decorated, despite his shyness. James gets the idea of having a competition for the "Best Dressed Engine." When Marie arrives and hears about a competition, she wants to join in, but James tells her that she needs to be decorated since it is a Best Dressed Engine contest. Marie rejects the competition after hearing everything.
Later, Marie is crossing a bridge when a banner is blown onto her front. Since Marie is pulling the express, she cannot stop and so remains "dressed up." Trevor is pulling a cart of apples for the children's apple bobbing. When he hears Marie's whistle, he tries to go as fast as he can, but it is no use and Marie smashes all the apples. Jennifer is the last to reach the station for the contest, until Marie arrives. Everyone is surprised that Marie is decorated, (even Marie admits she never wanted to), but Jennifer says that she is definitely the Best Dressed Engine. Everyone agrees and Marie is announced the winner of the competition.