Hubert the Human Cannonball comes to Sesame Street to be launched out of a cannon into a bucket of blue gelatin. He enlists Baby Bear, Elmo, and Telly to help him, but things don't exactly go as planned! Plus, James Marsden stops by to explain the word "engineer." The fun continues with Abby's Flying Fairy School and Bert and Ernie's Great Adventures. Murray experiments with a rocket, and Elmo lends a helping hand in Elmo's World.