TMNT in... Mayhem From Mutant Island!!! is an animated short anthology series by 4Kids Entertainment. The story is broken down into "Chapters". Chapter Three debuted on 4Kids' website on Friday, March 6, 2009, with Chapters One and Two airing during TMNT: Back to the Sewer and Chaotic: M'arillian Invasion, respectively, on Saturday, March 7, 2009. They were streamed on the 4Kids website a week in advance of airing them on television. The episodes comprise a single story called "Mayhem from Mutant Island." The series uses TMNT: Back to the Sewer's art style and character designs. Thirteen "Chapters" in all have been made, ranging from 90 seconds to two minutes in length. On March 27, 2010 the shorts were edited together and re-aired under just the "Mayhem from Mutant Island" title as a new TMNT: Back to the Sewer episode.
- Donatello (Sam Riegel)
- Leonardo (Michael Sinterniklaas)
- Michelangelo (Wayne Grayson)
- Raphael (Frank Frankson)
- Chomper Bug
- Winged Dino
- Purple Dragons
- Baxter Stockman
- Master Khan
- Cyber Foot
Chapter 1: What Lurks Beneath!
The four Turtles are out perusing their 'extreme sports' gear, showing off to one another. Michelangelo attempts to jump a pothole on his skateboard, when the street around the pothole crumbles, dropping him into the sewer. There, a Chomper Bug captures him.
Chapter 2: Terror Unleashed
The Turtles beat down the Chomper Bug, and the street gives way again, dropping the bug and the Turtles into the sewer. The Chomper Bug scampers away, returning with Stego, Winged Dino, and Scorpion.
Chapter 3: Trouble Runs Rampant!
Airdate: 3/6/2009 (online) 3/14/2009 (TV)
The Turtles face down the dinosaurs in the sewers. Leonardo indicates that they need an upgrade to take on the dinosaurs, and the four of them suit up in battle gear..
Chapter 4: Showdown in the Subterrane!
Airdate: 3/13/2009 (online) 3/21/2009 (TV)
The Turtles slay the dinosaurs and bugs with their new gear, which causes them to explode into yellow-green goo. Donatello theorizes that the abandoned sewer in which they are fighting the monsters is not an 'ordinary' one, as he wipes sludge off of a door, revealing the Purple Dragons logo. The door swings open, revealing several Purple Dragon members and Hun on the other side.
Chapter 5: Attack of the Purple Dragons!
Airdate: 3/20/2009 (online) 3/28/2009 (TV)
The Turtles soundly defeat the Purple Dragons, culminating with Raphael constricting Hun from a rafter. The Turtles interrogate Hun about the monsters' origins, and Baxter Stockman, viewing the action from a computer console, gloats about how they won't get their answers from Hun.
Chapter 6: Face-Off With the Foot!
Airdate: 3/27/2009 (online) 4/4/2009 (TV)
The Turtles wield together some advanced armor and weaponry, and relay how Hun told them The Foot was behind the monstrous beasts they had faced earlier. Using the Turtle Hauler, they tunnel beneath Foot Headquarters, interrupting Master Khan's pep talk to his minions regarding attacking New York City.
Chapter 7: Rivals Take Arms
Airdate: 4/3/2009 (online) 4/11/2009 (TV)
The Turtles battle the Foot. Khan gets the upper hand on Leonardo, and Michelangelo attempts to save him with the Turtle Hauler's missile launcher. Unfortunately, Mike ends up hitting a column, causing some of the ceiling to fall on the Turtles. The chapter ends with Khan and the Foot advancing towards the Turtles.
Chapter 8: Dread Returns!
Airdate: 4/10/2009 (online) 4/18/2009 (TV)
The Foot continue to advance towards the Turtles, but suddenly grow frightened and flee. Michelangelo believes himself to be the catalyst of their foes' retreat, but a T-Rex is revealed to be behind him. The Turtles enage the dinosaur in battle, and Leonardo launches himself from the front loader on the Turtle Hauler for an attempted air rush attack. However, the T-Rex catches Leo in his mouth, closing its jaws around him.
Chapter 9: In Pursuit of Danger
Airdate: 4/17/2009 (online) 4/25/2009 (TV)
Leo almost gets eaten by a T-Rex but manages to free himself. However, the T-Rex grabs Leo again and tries to escape in the sewers with the Turtle. Leo's brothers chase the dinosaur through the tunnels and fire missiles at it from the Shell Wagon until Leo is finally free. However, the T-Rex returns, with some friends!
Chapter 10: The Scourge Revealed!
Airdate: 4/24/2009 (online) 5/2/2009 (TV)
After the Turtles manage to defeat the dinosaurs using the weapons in their car, Baxter Stockman finally reveals himself as the big bad behind all the madness and challenges the Turtles to defeat him.
Chapter 11: Rendezvous With Evil!
Airdate: 5/1/2009 (online) 5/9/2009 (TV)
The Turtles arrive on Baxter's mutant island, and start fighting his dino's. When Baxter manages to blast the Turtles out of the sky, he thinks to have finally won and be able to take over New York, but the Turtles still live and have once again new battle armor to fight with.
Chapter 12: Stockman Strikes!
Airdate: 5/8/2009 (online) 5/16/2009 (TV)
Stockman's dino's continue to attack the Turtle, who demonstrate their new heavy metal armor that can transform into various vehicles. While chasing Stockman, Don discovers that the villain radio controls the dino's using an antenna. Don tries to destroy it, but before he can some flying dino's kidnap him and fly him up high in the sky!
Chapter 13: Fate of the Deranged Dinos
Airdate: 5/18/2009 (online) 5/23/2009 (TV)
Raph rescues Don who finally destroys the antenna. This restores the dino's back to their normal, docile selfs. The Turtles "borrow" Stockman's boat to return home. Curious to find out why there is no more fighting to hear, Stockman comes out of his lair and gets chased by the friendly dinos who want to become his friend.
- The 13 Mayhem From Mutant Island Interstitials/Shorts were written by Matthew and John Drdek.
- The dinosaurs the Turtles face are similar to the Paleo Patrol Mini-Mutant figures. The suits the Turtles don in Chapter Three are the Sub-Sewer outfits from the action figures.
- The T-Rex that appears in Chapter Eight sports the same design as the one briefly seen in Web Wranglers.
- When aired as a single episode, a different opening sequence was featured. While re-using the same theme music, different clips were featured. This opening was previously seen in the rerun of "Wedding Bells and Bytes" that aired with the top 10.