The series is set 97 years after a devastating nuclear war wiped out almost all life on Earth. The only known survivors are the residents of twelve space stations in Earth's orbit prior to the war. The space stations banded together to form a single massive station named "The Ark", where about 2,400 people live. Resources are scarce and all crimes no matter their nature or severity are punishable by death ("floating") unless the perpetrator is under 18 years of age. After the Ark's life support systems are found to be critically failing, one hundred juvenile prisoners are declared "expendable" and sent to the surface in a last ditch attempt to determine if Earth is habitable again. The teens arrive on a beautiful planet they've only seen from space. Confronting the dangers of this rugged new world, they struggle to form a tentative community. However they discover that not all humanity was wiped out. There are people on Earth who survived the war, called "grounders" by the 100. The ...

Michael returns home from military school to find his mother happily in love and living with her new boyfriend. As the two men get to know each other, he becomes more and more suspicious of the man who is always there with a helpful hand.

The four turtles travel back in time to the days of the legendary and deadly samurai in ancient Japan, where they train to perfect the art of becoming one. The turtles also assist a small village in an uprising.

The turtles find out where the Ooze, the substance which made them mutate, came from. Unfortunately Shredder learns about it too, and uses it to enhance himself. So the turtles have to prove again who's the better ninja fighter.