Batman discovers a group of homeless children forced to steal for a cruel, deranged man called the Sewer King.
- Absurdly Spacious Sewer
- Abusive Parents: The Sewer King sees himself as a good parent to his "beloved children", even though he orders them to steal for him, punishes them severely for talking, and makes them live in deplorable conditions.
- Adult Fear: Batman is logically angry when Frog picks up and plays with a decorative gun on the wall of Wayne Manor, since it could have been loaded.
- Evil Cannot Comprehend Good: The Sewer King couldn't understand why Batman would bother saving his life.
- The Fagin: The Sewer King is the evil version.
- First Time in the Sun: In the end, the Sewer King's captured orphans are brought into the sunlight at last.
- King of the Homeless: The Sewer King.
- Light Is Not Good: The Sewer King punishes a child for breaking his rule against "talking" (he cried out after injuring himself) by locking him in a room filled with bright lights for several hours. Averted at the end when the orphans enter the daylight again.
- Monster of the Week: The episode spotlighted a villain called the Sewer King who never appeared again. He was sufficiently creepy for a Batman villain, but it's just as well he never returned, since he was really only good for one story (that is, showcasing the evils of child slavery).
- Mook Horror Show: A kids version as Frog attempts to escape Batman through the sewers that he knows like the back of his hand, only to find there is no escape from the Dark Knight no matter where he goes.
- The Sewer King has an adult version as he learns to his growing terror how relentless Batman can be when he chasing a villain down.
- Papa Wolf: Batman was enraged by Sewer King's crimes against the orphans.
- Reckless Gun Usage: While being chased by Alfred in the Wayne mansion, Frog finds a collection of antique firearms. He grabs a blunderbuss off the wall and waves it around like a toy. Alfred immediately backs off, but Batman jumps in and grabs the gun out of the boy's hands. Batman notes, "It's not loaded, but it could have been."
- Save the Villain: Given the nature of the villain's crime, Batman seriously thought about averting the trope this time but it was eventually played straight.
- Suddenly Voiced: Frog gets a line at the end of the episode.
- Thou Shalt Not Kill: Batman still goes by this, but he let the Sewer King know that he was sorely tempted to break it this time.
- Notably, when they're fighting earlier in the episode, Batman inadvertently causes the Sewer King to fall into the pool of water they're fighting above. Batman sees the alligators going into the water after him, thinking that they're going to eat the Sewer King...and Batman simply comments on how appropriate a fate it is for him.
- The Voiceless: The Sewer King, believing that children should be seen and not heard, forces his charges to be silent at all times... or else.