March is the beginning of baseball season and Arthur and his friends are eager to start playing. But the coach has told them they need to come early and warm up their arms and legs before they actually begin a game.  He explains how important it is to stretch and flex and get their muscles loose to prevent injuries.

Binky doesn't like getting up early, and even though his teammates have warned him that he needs to warm up before a game, he just laughs at them. But then disaster strikes. Binky becomes injured and has to sit on the sidelines while his friends are having all the fun out on the baseball field. What will Binky do now so he can feel like he's still part of the team?