When his class visits the aquarium, Charlie puts her pet goldfish, Wishy, in a plastic bag and takes him along in his backpack. As sea jellies, barracudas, and dolphins dazzle the class, Charlie explains all of the fun facts he is learning to Wishy. but soon Charlie gets caught up in the excitement. Before he knows it, his backpack, with Wishy in it, is lost, and everyone in his class must search the entire aquarium to help find Wishy.