George is excited to attend his first costume party, but there's just one problem—he doesn't have a costume! Will the mischievous little monkey be able to find the perfect one without starting too much trouble? Mrs. Gray's party isn't just any party—it's a costume party, and George and the man with the yellow hat aren’t wearing costumes! No matter—there are plenty in an old trunk upstairs, and soon George is trying on all kinds of outfits. But it's not long before George gets in the bed sheets. His new look may give the guests a scare at first, but in the end George is the life of the party!