The zoo has a new inhabitant. The pool must be enlarged, so that the hippopotamus baby has enough space. Due to the construction noise, neighbor Baron von Zwiebelschreck feels disturbed. With the help of the mayor he can stop the construction work. But Benjamin and the zoo animals continue to build. Completely annoyed, the baron rams piles into the river to stop the flow of water. One thing the Baron did not consider: Through this action his own property is flooded. Benjamin and the zoo residents are not vindictive. They help the baron, and so the good neighborhood is restored.