The first season of Teenage Mutant Ninja Turtles aired on Nickelodeon from September 29, 2012 to August 8, 2013. The season introduces four turtles, Leonardo, Donatello, Raphael and Michelangelo.
For fifteen years, four mutant Turtles and their rodent sensei have lived a secret life beneath the sewers of New York. Coming to the surface for the first time, the Turtles soon find their day out interrupted as a young girl and her father become the targets of mysterious, and dangerous, men...
When April O'Neil is abducted, the Turtles search leads to the base of the robotic Kraang army, and Leonardo struggles to unify his rebellious brothers to victory.
The Turtles are in danger of exposure when hot-headed Raphael is caught on video arguing with a human on the street. He must learn to control his temper in order to help the others retrieve the video before it falls into the wrong hands.
To prove that Turtles can be friends with humans, Michelangelo uses a social networking site to befriend a famous martial artist who is secretly Shredder's top lieutenant.
When Donatello's latest invention gives failed inventor and perpetual loser Baxter Stockman enhanced abilities, the turtles must learn to use their heads instead of brute force to defeat him.
When Donatello loses confidence in his bo staff as an effective weapon, he constructs Metalhead, a fully armed robotic turtle based on Kraang technology.
After April receives a warning from her imprisoned father, she and the Turtles embark on a mission to save him and stop The Kraang from detonating a mutagen bomb in the city.
When simultaneous threats from the Purple Dragons and Baxter Stockman’s mechanical Mousers force the Turtles to split into two groups, Donnie & Mikey must prove that their “B Team” is just as valuable as Leo & Raph’s “A Team.
Michelangelo befriends Leatherhead, an unstable mutant alligator who possesses a strange piece of Kraang technology, but the other Turtles aren’t sure whether Leatherhead is a friend or a foe.
Snakeweed returns and begins abducting people. Tired of Raphael's constant criticism while trying to stop Snakeweed, Leonardo lets Raphael try his hand at leadership. While away from the group, Leonardo meets a female Foot Ninja named Karai, who tries to lure him to the dark side.
While breaking into the hostile environment of TCRI headquarters, the Turtles discover the true intent of the Kraang and resolve to stop the alien invasion once and for all.
After witnessing the Kraang in action, Karai realizes the seriousness of the alien threat and proposes an alliance with the Turtles....unless the Shredder finds out.
When Shredder plans to create an army of mutants, the Turtles must rely on the help of the Pulverizer, who was recruited into the Foot (to be expendable) and volunteers to gather information on the inside on their behalf. When he agrees to be a test subject for a stolen supply of Kraang Mutagen, the Turtles rescue him, but not before he recklessly gets himself mutated.
Donatello breaks into a secret Kraang detention center in order to rescue Kirby O'Neil, but ends up trapped inside with a deadly prisoner called the Newtralizer.
