Four turtles fall into the sewers and are befriended by Hamato Yoshi a Japanese man sent to New York who was forced to live in the sewers. One day he sees a strange green glow which transforms the four turtles into human-like creatures. Hamato (now Master Splinter) changes into a giant rat from the green glow and teaches the turtles the skills of the ninja as they team up with news reporter April O'Neil to battle against Yoshi's arch enemy Shredder and Krang, an alien warlord from Dimension X.

The Teenage Mutant Ninja Turtles are back in an all-new animated series on Nickelodeon! Surfacing topside for the first time on their fifteenth birthday, the titular turtles, Leonardo, Michelangelo, Raphael and Donatello, find that life out of the sewers isn't exactly what they thought it would be. Now the turtles must work together as a team to take on new enemies that arise to take over New York City.

When four pet turtles were bathed in alien ooze, they began to mutate and became the Teenage Mutant Ninja Turtles. Raised in New York City sewers by their foster father and wise sensei, Master Splinter, Leonardo, Michelangelo, Donatello, and Raphael wage war against crime. Led by Master Splinter, the four turtles learn the ancient martial art of Ninjitsu, mastering skills of stealth, weapons, and fighting. They stop evildoers in all forms, whether barbaric gangs, lowlife crooks, deranged cyborgs, or even the crime syndicate The Foot, led by their archrival, The Shredder.

The Turtles — Leo, Raph, Donnie and Mikey — each will go it alone for the first time. Faced with new threats and teaming up with old allies, the Turtles will discover who they really are when they don’t have their brothers at their sides.