Heathcliff accidentally solves a Rubik's cubetype puzzle, so Iggy decides his cat must be a genius and submits him to a scientist for laboratory testing. Heathcliff doesn't blend well with the other animals, and in no time has managed to cause countless squabbles and sabotage all the lab tests./Cleo is bored with Westminster and asks Riff to take them to the exciting city. The cats build a giant balloon and fly it into the city. Once there, another gang quickly steals their balloon, leading to a chase across town.