The Turtles must steal the Heart of Tengu from Karai so Agent Bishop will cure their brother. In the meantime, Leatherhead and Stockman work together to develop a cure for Donatello and the outbreak virus.
This episode contains examples of:
- Alternate Identity Amnesia: While Donatello is aware of what exactly happened to him, he doesn't seem to have memory of his time as a monster, and one of the things he says after being cured is hoping he didn't cause much trouble for the rest.
- Area 51: Bishop's base, of course.
- Big Brother Instinct: Inverted. In the end, a revived Don asks everyone if he caused them any trouble in his feral state. Everyone gets quiet and awkwardly look around at each other. Then Michelangelo flashes a wide grin.Mike: Nah.
- Big "NO!": Karai, when the Turtles escape with the Heart of Tengu.
- Big "WHAT?!":
- Splinter, when Stockman admits that Bishop lied about having a cure.
- Stockman's reaction to Bishop saying Leatherhead is smarter than him.
- Bittersweet Ending: Donny is cured of his condition, and Bishop uses the antidote to end the outbreak in New York, but as he inadvertently destroys the Heart of Tengu, he frees the Foot Mystics from Karai's control, allowing them to carry out their own agenda.
- Can't Kill You, Still Need You: Invoked by Bishop to keep Leatherhead from killing him. He admits to lying about having a cure, but he boasts he's the only one that can get Stockman to produce one, so he knows Leatherhead can't lay a claw on him without Donatello suffering for it.
- Character Development: Once again, the Turtles have to break into the Shredder's headquarters, but Michelangelo is far more focused this time around, as Don's life depends on the mission. He also notes how suspicious it is that Bishop knows exactly where the Heart of Tengu is. He also tells Leo to focus when he briefly contemplates accepting Karai's challenge.
- The End... Or Is It?: Donatello is cured and the heroes go home, but the Mystics are now free of Karai's control and intend to resurrect the true Shredder.
- Enemy Mine: The Turtles, Splinter and Leatherhead team up with Bishop and Stockman to cure Don and stop the outbreak.
- False Reassurance: What Bishop was giving the Turtles when he told them he could cure Donnie's secondary mutation.
- Find the Cure!: Leatherhead and Stockman work together to develop a cure for the outbreak virus, and Bishop does give a sample to Donnie when the other Turtles uphold their agreement.
- Foreshadowing:
- The Mystics letting Leo and Mikey pass without a fight hints at their endgame.
- Karai's horrified reaction to losing the Heart of Tengu foreshadows she knows exactly what's going to happen now that the Mystics are going to get free.
- The ending of the episode sees the Mystics declare they are free to resurrect the "true" Shredder. This will not be properly explained until early next season.
- Genre Blindness: The Foot Mystics note how Karai thought she could keep them under control since they could not touch the Heart of Tengu.
- Hoist by His Own Petard: Raphael happily uses one of the Shrednaut units to attack the Foot and tear up the place.
- I Gave My Word: Though he lied about already having a cure, Bishop does uphold his end of the agreement once the Turtles come through with theirs.
- I Lied: Bishop lied about having a cure so the Turtles would help him.
- Ironic Echo: Bishop manipulates the Turtles into getting the Heart of Tengu for him and although he holds up his end of the bargain by curing Don, he gives the Turtles fifteen minutes to vacate the premises as he prepares to destroy his base and bids them farewell by saying "Pleasure doing business with you". Then the Foot mystics manipulate Bishop and Stockman into destroying the Heart of Tengu (after manipulating Bishop into stealing it) and then one of them bids them farewell by saying "It was a pleasure doing business with you, Agent Bishop."
- Lampshade Hanging: Getting into Foot headquarters requires knocking the main power out and slipping in before the emergency power reactivates the security systems. April devised a computer virus to be uploaded into the power station, but it's the tech-illiterate Casey going in disguised as a janitor. He questions this approach, but April says he's the one that looks like a janitor.
- Laser-Guided Karma:
- After spending several seasons and this episode manipulating people in his favor, it's time Bishop gets a bit of what it feels like by the Foot Mystics.
- Though there to steal the Heart of Tengu, the Turtles still end up paying Karai back for the destruction of their lair by inflicting damage on the Foot's headquarters and tech.
- MacGuffin: The Heart of Tengu.
- Nerves of Steel:
- Upon learning Bishop lied about having a cure, Leatherhead starts losing control and is ready to rip him limb from limb. Bishop reminds him he's the only one who can get Stockman to make the cure, staying completely calm the entire time.
- Mikey's not looking forward to being around the Foot Mystics again, but Leo says this room is the fastest way to the Heart of Tengu and insists they go through.
- Oh, Crap!: When Leo and Mikey find themselves in the room with the Foot Mystics.
- O.O.C. Is Serious Business: Possibly the only moment in the series where Leo almost gets distracted on a mission (when Karai arrives and tries to goad him into a fight) and Mikey is telling him to stay focused.
- Percussive Shutdown: At the power station, Casey uploads the computer virus as planned, but it's not working and the Turtles are at risk of getting fried by the furnace. Casey gets so sick of this that he resorts to picking up a monitor and throwing into the other equipment, thus knocking out power across the city.
- Poor Communication Kills: Both the Turtles and the Foot are not on speaking terms, with good reasons mind you. But if they had, they would have found out that the Foot Mystics were up to no good.
- Properly Paranoid:
- Mikey finds it suspicious that Bishop knows the exact location of the Heart of Tengu. He also questions why the Mystics didn't attack them.
- After the power is knocked out, Karai knows that Leonardo is in the building.
- Race Against the Clock:
- Donatello's condition is rapidly deteriorating, meaning not much time either for Leatherhead and Stockman to develop a cure or for the other Turtles to steal the Heart of Tengu.
- Minor example when it's all over. Bishop says the heroes have compromised his base, so he has triggered a self-destruct. He says they have 15 minutes to get Donatello and evacuate.
- Red Eyes, Take Warning: The Foot Mystics in general, but when Leo and Mikey are passing them, they look like colorless statues. It's only after the Turtles leave in the elevator that one Mystics' eyes suddenly light up and color returns.
- Sadistic Choice: Leo's opening narration acknowledges how stealing the Heart of Tengu from Karai is an impossible mission, but also how the only other option is watching Donatello die.
- Shout-Out:
- Mikey references The Wizard of Oz when Casey blows a hole in the wall.
- "A wise man once said, 'I've got a bad feeling about this.'"
- Skewed Priorities: Subverted. Leo almost gives into Karai's challenge to fight, but Mikey talks him out of it.
- Teeth-Clenched Teamwork: After being convinced that allowing Bishop and Stockman to live is the only way they can save Donnie's life, Leatherhead begrudgingly agrees to stand down. He then begins working cordially alongside Stockman and is so effective he actually finds a cure for the plague, and even endures further taunts from his enemies without a fuss.
- Trap Is the Only Option: Mikey doesn't want to go through the Foot Mystics' room, stating that it's an obvious trap. Leo insists they have no choice. Subverted when it turns out not to be a trap at all because the Foot Mystics want the Turtles to succeed.
- Unwitting Pawn: Bishop and, by extension, the Turtles.
- Villain Respect: Seeing Leatherhead at work and getting results, Bishop commends his intelligence and says he was wrong to try to dissect him. He even calls him more brilliant than Stockman.
- We Need a Distraction: Raph's role in the heist of the Foot Headquarters.
- Wham Line: "And we are free... free to resurrect the true Shredder!"
- Wrong Genre Savvy: Leo and Mikey expect alarms to sound the moment they steal the Heart of Tengu. Nothing happens, and they express relief... only for Karai to casually walk in and be surprised to see them.
