Lisa ventures into a sewage treatment plant in Chicago.Film inserts: Msima Spring in Kenya houses a massive food chain, and it all centers around hippos; the recycling of aluminum cans; leaf-cutter ants.ANIMATION: Gloria wants to be a mechanic.THE BLOODHOUND GANG: ""The Case of the Missing Bloodhound, Part One."" Mr. Bloodhound has been kidnapped prior to a trial, and he has sent a message which the gang deciphers. (Concludes in next episode.)