A class trip to the zoo turns into a hunting expedition for a devious and prank-playing hippo. The teacher, the zookeeper and an enthusiastic pack of pint-sized students charge here and there to capture that missing beast. The noise and drama reaches a crescendo as each child thinks they have bagged the prize... the missing hippo! Poor little Liam is left out, is way behind the pack, and unheard. Clever little Liam spots the trickster every time but no one will pay any attention his contribution. Will anyone stop the chaotic search and finally listen to him? Will Liam get acknowledged and rewarded when those around him realize he is a hippo-finding-hero?