Ms. Frizzle's class is visiting the zoo, which is, according to Tim, the only place in the city where wild animals can survive. To test this idea — ZAP! — Ms. Frizzle turns the class into possums, foxes, and falcons! The Bus, with Liz inside, bec... (more)omes a bear and wanders off, looking for food. Will the kid-animals be able to find the Bus-bear before the zookeeper finds it? And is Tim right? Can animals (like themselves) survive in the city?