Mary is always neat and organized, while Harry is horribly messy. But even Mary's carefully planned schedule can't help when things go wrong at her own birthday party. The party is supposed to start with the kids from Room 3B taking an exciting train ride, but when their train is delayed not one . . . not two . . . but three times, Mary's plan is completely ruined! She thinks the only thing that can make her feel better is cup after cup of sugary Island Punch—even after her mom tells her to stop. But what Mary doesn't know is that Harry has his own wacky ideas for saving Mary's big day. Can the kids still have fun even when nothing's going the way it's supposed to, or will this be the most horrible birthday ever?