Ms. Frizzle's class needs a mascot for its soccer team. Phoebe wants it to be a butterfly but everyone else thinks that a dumb idea, butterflies are too wimpy! Know-it-all Janet suggests a Bog Beast mascot. The kids think that sound really cool but just what is a Bog Beast? Find out when you join the class on a exciting field trip to a real live bog, where they learn all about Big Beasts and butterflies.