Season 4

The Turtles hide out at Casey's farm to recover from their battle with the Shredder. However the ghosts of Casey's past come back to haunt him when his cousin Sid arrives with a gang in tow...

The Turtles bear witness to a rumble in the urban jungle between two alien princesses, fighting for the right to party and rule. Pistols at twenty paces. Tally ho.

Ascending to new heights, the Turtles aid the winged warrior named Raptarr against the renegade Mephos to save the floating city of the Avians.

The Turtles face a species of the deep, and when April gets too close to the action, she grasps a truth behind the current of environmental consequence.

Casey and Leo investigate a series of large-scale robberies. Not surprisingly, Hun and the Purple Dragon are to blame. However one of their hauls is a crate that should never have been opened!

Casey and the Turtles are practising their hide-and-seek skills at an abandoned warehouse complex. All the while, a strangely familiar figure watches them from the shadows - with an army of rats at his command!

A return to the Battle Nexus, a time to fight, is Mikey bound for glory once more?

On Halloween night, a mustachioed man visits April, expressing interest in a rather unusual item: a hideous six-armed idol. But the statue is no ordinary junkshop knickknack; it can be used to invoke a horde of imps that proceed to clean out the city and bring its spoils to their master, a criminal who calls himself The King of Thieves.

The Turtles learn first hand what it means to have a "Bad Shell Day" as calamity after calamity befalls them. This time the Turtles may not be able to save everybody...

When the President of the United States arrives in New York City, an invasion of what seems to be aliens attacks at the most inconvenient time. However, the Turtles investigate this "invasion" and find out that Bishop is behind it. The question is - why?

The Purple Dragons have evolved from a basic street gang to a smuggling syndicate that works throughout New York. Leonardo goes with Casey to put an end to Hun's plans. However, Casey and the recently angry Leo will have to control their own fury if they want to bring justice-- and not just veangeance-- out of this.

The Turtles help Nobody protect an old man when he witnesses Jengo, leader of the Turks, harming a Turks member. Can the Turtles and Nobody stop the Turks?

Usagi and Gen come to New York for a visit with the Turtles. Gen gets a little carried away by the bright lights of the big city and goes wandering off on his own. And if the modern world wasn't dangerous enough, an assassin from Usagi's world has followed Usagi and Gen. His target: Leonardo.

It is time for Leonardo to move on. Splinter sends Leo to a new sensei, or rather, a very old sensei. The journey is long and perilous. Can Leonardo look into himself and find the right answers to his questions? Can he even find the right questions?

While Leonardo is in Japan studying with the Ancient One, Karai as the new Shredder makes her attack. Will Leo return to New York? Will he find out what happened to his home and his family? And, have Splinter and Turtles really been destroyed?

Leonardo returns from Japan to find the lair in ruins and his family nowhere to be seen. As he investigates he finds that the Foot is back to full strength - with Karai as their leader. Since the Foot believe Leo to be dead, he puts all that he has learnt from the Anicent One into practice...

Bishop has too deal with the consequenses of his actions when people and animals all over New York starts mutating into horrible beasts after his "alien" invasion.

For several years April's uncle Augustus (aka Augie) has been missing.

When the power goes out in their lair, the Turtles and Splinter gather around the candlelight as Leonardo tells a story he learned from the Ancient One about Splinter's sensei, Hamato Yoshi.

Savanti Romero plots his revenge against the Turtles and Renet after they had him banished to the Cretaceous period. Using his magic to manipulate time, Romero lures the Turtles and Renet into a trap to obtain the time sceptre.

Having travelled to the past, the Turtles and Renet battle with Savanti Romero and his telepathically controlled dinosaurs as Savanti attempts to change the historic timeline by preventing the dinosaur extinction event.

With the outbreak-mutant situation the Turtles feel they have to deal with and Donatello sick his brothers leave him with Casey and April for care. But Donatello is not sick but in the last stages of a second mutation.

With Donatello sick the Turtles are desperate. So desperate that they decide to try and sneak into Bishops facility, where they realize they have to make a deal with the devil if they want to cure Donatello

To cure Donatello the Turtles made a deal with the devil aka Bishop. Now they have to retrive a pendant that is supposed to help Bishop in his research. The thing is that the pendant is in the heart of the Foot-building, and Karai won't just hand it over

After the Turtles were able to cure Donatello's mutation, a group of ninjas confronts the Turtles to tell them about a battle between good and evil that will decide the fate of the world.