The villains in this story are leprechauns. Well, not really, that's what some old lady said when some little kid dressed in green steals her purse at the beginning of the episode. Actually, the kids are known as "underdwellers," and they are not the villains, just captives of an evil man called "The Sewer King."
The kids, supposedly, were unwanted above ground and so he keeps them as his slaves, sending them up only to steal things. He and his "children" are protected by his "pretties" - gigantic alligators.
That's really the only intense part of this episode: Batman having to deal with these over-sized, hungry reptiles.
Some humor comes in earlier on when Batman captures one of these green-clad kids and poor Alfred attempts to feed and bathe the unruly kid
Other highlights: "You play chicken long enough, you fry," Batman tells two teens who were playing "chicken" on top of an el-train.
Once again, perhaps because the story wasn't as strong as in the first five episodes I watched (the DVD isn't in the same order as the episodes listed here), I paid more attention to the great '40s artwork. I just love the automobiles and Deco art style in which this stories are drawn. I do appreciate the artists who produced this fine series. It's a big reason I am entertained more with these than any other animated series I've seen,, whether action or comedy.