The New York City Sewer System - S2.E39

The Nutmeg travel to New York for a vacation. Grandpa spins a yarn about how it's rumored there are alligators living in the sewer system and whoever could capture one would be a hero. While visiting a museum, Grandpa leaves Heathcliff with the hatcheck girl...but not for long. Heathcliff soon escapes and before long he's down in the sewers beneath the Big Apple, searching for an alligator. When he actually runs into one the episode turns into a wild chase in the sewers as cat and reptile clash in a titanic battle.