01PLOT

Open with Splinter training vigorously in the Turtle Lair. Upon finishing, the Sensei moves to a room where he packs a pouch and begins to leave the lair. Splinter informs the Turtles that he will be gone for a few days and orders them not to leave the lair. Disobeying their father, the Turtles decide to follow him and they are lead to a dead end alley.

Splinter uses some chalk to draw a glyph on the wall and then begins to chant, creating a portal that he disappears into. Donatello pulls out an ultra-violet lamp that illuminates the faded glyph and Raphael traces it with some chalk. Leonardo then begins to repeat the chant that Master Splinter had used - and the portal reopens! The Turtles all enter and end up in a forest in some type of nexus between dimensions. They are met by four skinny, stick-like creatures (known as Gom-Tai) that attack them!

Leonardo's katanas are sheared in half during the battle. The Turtles realize that to defeat these foes, they'll have to get in close - and so they use various throws to defeat the Gom-Tai. After the skirmish, the Turtles are surprised to see the Gyoji float over, announcing them as a winner of the preliminary match (and calling them the Slontags). As the real Slontags appear through a portal, the confusion sets in as the Gyoji realizes that something is wrong. Taking the Slontags and Gom-Tai with him through a water portal, the Gyoji departs.

Still confused, the Turtles walk up a hill to see Splinter and a four-armed giant fighting. The Turtles advance to help their Sensei, but are stopped inside a force field created by Gyoji. The mystical referee states that there can be no interference in the competition. As the Turtles stand helpless, they see Splinter about to be crushed!

Master Splinter dodges his opponent and then delivers some mighty kicks to win the fight. The Turtles are released and they rush to congratulate their Sensei - but are greeted with a scolding for disobeying his wishes. The giant arises and the Turtles prepare to defend their master, but Splinter angrily intervenes. Gyoji announces that Master Splinter is the victor in this round, and the giant, whose name is D'Jinn, bows to Master Splinter. It turns out the two are old friends. D'Jinn is happy to meet Splinter's sons, but he's shocked to discover that their Sensei hasn't explained the Battle Nexus to them, nor told them about how he won the competition in the past. With that, D’Jinn explains how the Battle Nexus was created as an inter-dimensional tournament of fighters. The Turtles learn that Splinter’s sensei, Master Yoshi, was once the Battle Nexus champion, as was Splinter after he defeated Drako.

As D’Jinn continues, we discover that Drako and his four assassins were dishonorable and decided to attack the injured Splinter after the match. Luckily, a young Miyamoto Usagi was there to help defend the mutant rat. Unfortunately Usagi wasn’t enough help, as Drako was able to capture both of them. Fading out, we see Drako’s mouth about to chomp down on Splinter.

About to be chomped, Splinter and Usagi were saved by the Ultimate Daimyo, who blasted the evil dragon with his staff, forcing the villain to retreat.

Cut to present, where the Ultimate Daimyo appears with his son, the Ultimate Ninja. The ninja apologizes to Master Splinter for challenging Leonardo to a mortal duel in earlier days (episode 35). The Daimyo invites the Turtles to join the tournament - at first Splinter is reluctant to allow this, but then he realizes that they are ready and gives them permission to fight. The Daimyo arranges for Gyoji to have Leo’s swords repaired

The Daimyo then teleports the group to the next stage of the tournament and addresses all the fighters. During this, the Turtles spot old friend Traximus among them. After the ceremony, the Turtles are escorted to the Pavilion of Past Champions where the Ultimate Ninja shows them statues of Hamato Yoshi and Splinter. As the group departs, Leo asks to stay behind for a moment. Facing the statues, Leo bows his head in respect and meditates for a moment - oblivious to the appearance of a group of Dark Ninja assassins. We fade out just as one assassin aims its crossbow at Leonardo's back...