Teenage Mutant Ninja Turtles: Mutant Mayhem

Cynthia Utrom, executive of TCRI, sends a team to locate the rogue scientist Baxter Stockman, who has created a mutagenic ooze. In a chaotic explosion during their pursuit, Stockman meets his demise, and the mutagen seeps into the sewers of New York City, enabling a lone mutant housefly to escape.

As the mutagen spreads throughout the sewers, it transforms four turtle brothers—Leonardo, Michelangelo, Raphael, and Donatello—along with a rat named Splinter into humanoid mutants. Embracing their new forms, they are cautioned by Splinter, who insists they must remain hidden from humans to avoid trouble.

Years pass as the turtles yearn for acceptance in human society, despite Splinter’s warnings about their safety as mutants. Splinter trains his sons in Ninjutsu but restricts their excursions to petty thefts to survive, leading to their growing frustration and desire for freedom.

Fifteen years after their transformation, the turtles practice their Ninjutsu skills on a rooftop but accidentally injure a girl on the street with a ninja star. Although she is unharmed aside from her helmet, the situation escalates when her scooter is stolen, prompting the turtles to take action.

The turtles pursue the scofflaw who took the girl's scooter to a warehouse, where they engage in their first real fight. They successfully dismantle a criminal gang operating in the area and retrieve a stolen moped belonging to a teenager named April O'Neil.

After their successful confrontation, the turtles meet April O'Neil, who expresses her fascination with their story. As she shares her aspirations as a journalist, she reveals her investigations into a series of thefts involving TCRI tech orchestrated by a criminal named Superfly.

In response to the thefts, Cynthia Utrom implements tracking devices on TCRI technology, making the turtles aware of the growing danger. The turtles, motivated by their desire for acceptance, decide to utilize April’s journalism to change how the world views them and thwart Superfly's operations.

The turtles confront henchmen assisting in the thefts and eventually meet Superfly, who reveals his true identity as a mutant. Superfly introduces them to his gang, which includes notable villains like Rocksteady and Bebop, and they bond over their shared experiences as mutants.

Superfly unveils his grand plan to utilize the stolen technology to mutate all animals on Earth. His goal is to establish mutant supremacy over humans and weaponize mutagen to turn humans into pets, increasing the urgency for the turtles to stop him.

As the turtles attempt to thwart Superfly’s plans, they find themselves captured alongside their allies. At TCRI headquarters, Cynthia begins extracting their mutagen to produce super soldiers, putting the turtles and the city's safety at risk.

In a desperate rescue attempt, April and Splinter work together to save the captured turtles. Their timely intervention allows the turtles to confront Superfly, shifting the dynamics of the battle against the oppressive figurehead and his gang.

The turtles and Splinter engage Superfly and his gang in a climactic battle, urging them to reconsider their violent intentions. After a fierce struggle, they manage to take down Superfly, but not before a catastrophic mutagen spill transforms him into a colossal kaiju.

With Superfly unleashed in kaiju form, the turtles now face the mistaken perception of being monsters themselves. They unite with April and the citizens of New York to combat the rampaging Superfly, striving to restore peace and their heroic image.

Following their triumph over Superfly, the turtles are embraced by the city as heroes. They move into their sewer home, foster relationships within the mutant community, and begin attending high school with April, finally experiencing acceptance.

As the turtles celebrate their newly-found acceptance at prom, they remain oblivious to Cynthia’s schemes. She is seen plotting with the enigmatic Shredder, suggesting that new challenges lie ahead for the mutant heroes.