Intro: Michelangelo explains the death of Utrom-Shredder and the other events of the previous episode. End with Foot warehouse crashing down atop the Turtles…
Act 1: Open with TMNT having saved themselves from the imploding warehouse by hiding under a support beam. Leo and Raph argue and Don tells them to continue the fight later - right now they need to get to safety. The guys leap out from under the falling walls as their protective girder shatters. As soon as they get solid footing, Baxter Stockman's assault robot emerges from the wreckage and attacks everyone in sight. The Turtles and the Foot are forced to cooperate with one another in attempt to defeat the mechanical monstrosity. The fight spills onto the streets, where the robot turns its attention to an oncoming bus and fires at it, causing it to crash. All of the passengers save one escape, and Leo rushes to help the man. Raph gets agitated that Leo will be seen by humans, but Leo yells that an innocent life is at stake and enters the overturned vehicle. A man inside is trapped under some sheet metal, which Leonardo lifts. The man asks what the ninja is, and Leo explains that he's a figment of the fellow's imagination - he took a pretty hard blow to the head. The Turtle assists the man out of the bus and then rejoins the battle against the robot.
Cut to inside Karai’s lear jet. Her assistants hand her a laptop computer, which she uses to view video of Leonardo.
Back in NYC inside Purple Dragons’ HQ. Dragon Face is in the center ring, riling up the troops by telling them that they'll soon run the city. The thug is interrupted by the sudden appearance of Hun, who leaps from the rafters and casually pummels Dragon Face. Hun reclaims his position as leader of the gang and promises to take them to the top of the food chain - in honor of Shredder's memory.
On the streets, the battle with the mechanoid continues. Raphael jumps into a vacant bus and fires it up, intending to crash the vehicle into the robot. Unfortunately the 'bot is prepared and opens fire on it before it gets close.The bus rolls over and crashes. Leonardo hurries to rescue his brother.
Act 2: Raphael and Leonardo continue to argue as they struggle to free Raph. The robot ignites spilled fuel from vehicle… the trail of gas heading directly for the bus’ gas tank! Don yells for his brothers to get out of there - now! The bus explodes, but the Turtles managed to save themselves just in time.
The robot continues to attack, forcing everyone, Foot and Turtles, to take cover. Don spies some broken electrical cables and tells Mike to lead the robot in his direction. Michelangelo and some Foot Elite Guard get the mech to chase them - once it steps into a large puddle of water, Donatello drops the cables in and the power short circuits the 'bot. The Foot immediately turn on Mikey, who is forced to retreat. Raph and Leo want to help their brother, but suddenly two more robots appear and open fire!
Inside a truck nearby, Big Boss mobster and Baxter Stockman watch the battle, both happy with how their partnership is working out.
Meanwhile, Mikey is being chased through the rooftops of the Big Apple. Mike has eluded all but three of his pursuers, but manages to escape them by hiding in some laundry that's hanging on lines to dry.
Karai's plane lands in New York, and she and her aides exit the plane. Karai is dressed for battle.
Cut to April and Casey unpacking boxes in the newly renovated building housing her "2nd Time Around" antiques shop. Jones is helping O'Neil when Michelangelo shows up out of nowhere, scaring the woman, which causes her to drop a tray of antique dishes. O'Neil gets angry with her ninja friend and asks what he's up to. Mikey explains that he's running from the Foot - and April gets even more upset because she just got things fixed after the Foot blew up her old place! Mike feels embarrassed and prepares to go, but Casey wants to join in on the fight, so he grabs his vigilante gear. Jones asks for April's keys to her van, but O'Neil is reluctant to relinquish them. Casey says that in that case, he and Mikey will just hang out with her. April gets the point and tosses the keys to Jones, and he and Mikey head out. April watches from the doorway and whispers, "Be careful."
Cut back to the warehouse/robots/ninjas scene. S.W.A.T. teams arrive on the rooftops and prepare to attack - only to be attacked by Hun and his Purple Dragon gang instead! With police out of the way, the Dragons line the top of the building and aim their arsenal of weapons at the TMNT and Foot.
Act 3: The Dragons destroy one of Baxter's robots, thanks to Hun's bazooka. Seeing this, Big Boss and Stockman decide it's time for a hasty retreat, and Baxter starts the truck and takes off - right into the path of the remaining assault 'bot! Stockman notes the irony as the mech opens fire and causes the vehicle to crash.
Hun tries to kill the Turtles with a bazooka while Leo and Raph continue their ongoing argument. Up pulls Michelangelo and Casey in April's VW bus. The other three Turtles pile into the van as Hun fires after them, fortunately missing with each shot.
Leonardo takes the guys to a water tower that he's set up as a temporary base of operations. Raphael and Leo renew their argument. Outside, the group is being spied upon by Karai’s top aid, who plants a bomb on the tower. Raph and Leonardo's argument comes to a head, with Raph vowing to leave the group. As the fiery Turtle prepares to leave, the bomb explodes. The TMNT land on their feet on the rooftop below, but Casey bounces hard - fortunately he's not hurt.
Karai and her two aides appear, weapons drawn.
Act 4: Karai states that she wants to talk, but Raphael is angry and he attacks, despite Leo ordering him not to. A fight erupts between Karai and her two aides versus the Turtles and Casey. Karai nearly kills Raph, but Leonardo intervenes and a battle between the two leaders takes place. Mike, Don and Casey take on Karai's assistants, who outmatch our heroes. The battle isn't going particularly well for anyone - Karai kicks Leonardo to the ground and Raph renews his attack on her, but she evades him easily. Karai then leaps towards the fallen Leonardo, but before she can strike, he kicks her, sending her flying. Leo stands over her fallen body, and it appears that the Turtles have won - but Karai was only playing possum, and she kicks Leonardo to the ground yet again and then leaps onto him, her sword at his throat. Karai threatens to kill Leo unless the others back down and listen to what she has to say...