It's the night before Christmas-time to put out some cookies for Santa! But how did this tradition start? Elmo's dad spins him a bedtime story about his great-great-grandmonster, back when Sesame Street was a very different place. Why, everyone was so grouchy that Santa didn't even visit! With help from his friends, Elmo will bring kindness, holiday cheer, and the spirit of Christmas to Sesame Street. But will it be enough for Santa?