Billy’s off to a birthday party. He can’t wait! And neither can his Mini Monsters… they’ve snuck into the party too! Soon Gloop’s in the gelatin, Trumpet’s on a balloon, and Fang-Face is about to become the birthday surprise…

Billy is feeling nervous about his FIRST EVER school trip, so the Mini Monsters decide to come along too. They promise not to be any trouble…but who’s causing a commotion in the creepy-crawly cages? Why does the T. rex skeleton keep moving? And Billy can't help wondering about the really tiny Egyptian mummies… Can he save the trip from disaster?