April reports that a robotic-control microchip has been stolen by someone who chewed through the alarm system and broke through a titanium door. Leonardo rushes off to tell Splinter about this development, but their master has vanished without a trace. The only thing left behind is a videotape,
They play the videotape, which is Splinter announcing that he is no longer their master, and his final instructions are that they leave the lair and each go his own way. The Turtles are devastated, and immediately disagree about whether they should obey Splinter or not.
The Turtles sadly leave the lair and part ways, and a rat carries news of this to the Rat King. He and Leatherhead - who have joined forces - are delighted by the removal of their enemies, since they are planning to conquer the whole city. Leatherhead still wants revenge on the Turtles anyway.
Another robbery takes place at a different lab, but April is kept from investigating it because she has to cover rich child Rodney Van Gelt's birthday party. During the party, Raphael arrives and sings a song-o-gram birthday greeting from Rodney's parents. Leonardo is running a fitness center, Donatello is working at a fix-it shop, and Michelangelo has a series of short-lived cooking shows.
As April visits each of them in turn, a mysterious figure (clearly Splinter) is trailing her.
Shortly after being fired, Michelangelo is locked in a walk-in freezer by some rats. When he's frozen solid, the rats carry him off to the sewers, where the Rat King and Leatherhead are assembling robots shaped like rats and alligators.
Leonardo is practicing his ninja exercises when Leatherhead appears and attacks him. Since he's by himself, he has no chance against the larger mutant, and is knocked down through the floor. Raphael is hired to deliver a song-o-gram to a deserted warehouse, and is attacked by the Rat King and his rats.
April - who has realized the Rat King is involved after spotting him at the fix-it shop - rushes to tell Donatello, but arrives just as the shop is blown up. Fortunately, Donatello was warned with a minute to spare, and made his way into the sewer before he could be blown up. However, Leatherhead gasses and abducts him.
April follows Leatherhead to the warehouse and makes her way down an elevator shaft. Michelangelo, Donatello and Raphael are bound upside-down in the Rat King's lair, and Leatherhead claims that Leonardo is dead.
April is spotted as she arrives, she is unexpectedly rescued by Splinter before the Rat King's rats can swarm her. Leonardo also appears and reveals that he faked his fall through the floor, just before freeing the other three Turtles. They easily dispose of the robots, but the rats are about to overwhelm them when the elevator comes down with April and Splinter inside.
Splinter exerts his will over the rats, and commands them to destroy the robots. Leatherhead and the Rat King turn on each other as the rats flee the sewers, and they both flee in opposite directions.
Splinter explains that he knew that something involving Leatherhead and the Rat King was coming, but he believed that they could only deal with it if they pretended to separate. He has been watching them all (even phoning Donatello about the bomb), and says that separating them was also important because it shows how important it is for the five of them to remain together.
Back in the lair, Michelangelo makes them pizza, but cracks a joke that causes his brothers to chase him out of the room.
- Leonardo (Cam Clarke)
- Donatello (Barry Gordon)
- Michelangelo (Townsend Coleman)
- Raphael (Rob Paulsen)
- Splinter (Peter Renaday)
- April O'Neil (Renae Jacobs)
- Rat King (Townsend Coleman)
- Leatherhead (Jim Cummings)
- Burne Thompson (Pat Fraley)
- Rodney Van Gelt (Jennifer Darling)
- Rodney's butler (Pat Fraley)
- Turtle Lair
- Rat King's Lair
- Roseanne's Fitness Center
- Murray's Fix-It Shop
- Food a la Dude studio set
- Abandoned warehouse
- Song-O-Grams van
- Channel 6 Newsvan
- Medic car
Home media releases
- Teenage Mutant Ninja Turtles: Rebel Without a Fin
- Teenage Mutant Ninja Turtles Season 4
- Teenage Mutant Ninja Turtles: The Complete Classic Series Collection
- As the Turtles are on the street preparing to go their separate ways, Leonardo is seen with Michelangelo's colors.
- When Leonardo said "It's not much of a job" the blade of his sword on his belt was seen for a split-second.
- After Leonardo had finished his somersault at the gym prior to his fight with Leatherhead, the letter on his belt was missing.
- Raphael's belt letter was missing before he walked over to the warehouse elevator and after he jumped onto the crate to escape from the Rat King's rats.
- April breaks the fourth wall in this episode.
- In Leatherhead Meets the Rat King, Leatherhead and the Rat King were enemies, but they’re on the same side in this episode.