I, Monster (2012 TV series episode)

"I, Monster" is the thirteenth episode of the animated series Teenage Mutant Ninja Turtles (2012 TV series). It first aired on January 25, 2013.

Plot Synopsis
The episode opens up with an angry Dr. Victor Falco trying to re-create his psychic neuro-chemical. He apparently succeeds, but some of lab rats (that he's been experimenting on) chew through some power lines hanging near the ceiling and the lab catches on fire. Falco is severely injured, but thanks to his chemical, he is able to communicate with the rats and survive......

Meanwhile, in the Lair, the turtles are preparing to engage in a coordinated free-for-all with their sensei. At first, Splinter manages to dodge all of their attacks and evade them, but then Leo finally manages to strike Splinter in the face, but hesitates (which Splinter points out to him afterward), and is once again defeated. After Leonardo's "victory", the boys then declare that they may not need Splinter to teach them anymore, which visibly perturbs their sensei.

Meanwhile, Falco, now severely deformed, living amid millions of rats, and now living underground, calling himself "The Rat King", plots to subjugate the city to claim it for the rats. So, the rats quickly start to invade the city, causing huge panic and city-wide havoc. The Rat King then somehow becomes aware of Splinter through telepathy, and decides to try and control him - as he is 'a kindred spirit'. Rat King's words echo in Splinter's mind, which causes the latter to scream and fall to the ground. After the brothers come out to inspect their sensei, April calls Donnie, telling him that she is having a "pest problem" - Tons of rats are forcing her to take refuge on the top of a telephone pole. The turtles soon come to her aid - and manage to escape thousands and thousands of rats while doing so. After they rescue her, Donnie quickly figures that someone or something must be controlling every single rat in the city at once, thus meaning that Splinter could be at risk.

Back in the sewer lair, Splinter is fast asleep, but The Rat King has managed to get inside of his mind with hostile intentions!! Falco reminds him of his past losses; His family being slain, his mutation and his inner-rat. But Splinter mentally refuses to join him...The turtles soon arrive home, and - after Mikey pokes him several times just to make sure he's okay - Splinter wakes up and tells the turtles who the evil perpetrator is. Splinter says that The Rat King will not stop until he has complete control of the city and his mind; He then informs them of Falco's hideout, which he somehow was able to discover when Rat King was inside of his thoughts. April stays behind to look after Splinter, while the turtles head out to thwart The Rat King's plans.

The turtles find the junction underground, though are chased down by a gigantic wave of rats, whom they manage to escape from after a little while. Unfortunately, back in the lair, The Rat King has finally taken full control over Splinter and has made him helpless to defend himself in any way, shape, or form. Splinter attacks April, who is bringing him a cup of tea, but just when he is about to deliver the finishing blow, he is called to the Rat King's aid. The turtles soon locate the hideout, but Falco's new appearance is not the only revelation - Splinter is there as well!! Rat King breaks out in shrieks of sadistic laughter, and orders Splinter to attack the turtles, but when Leo yells "Sensei, DON'T!!", Splinter pauses for a moment. This causes The Rat King to uncover his mask, revealing his off-putting face and his everlasting creepy eyes. Leo hesitantly orders his brothers to take their own sensei down, but they end up having their butts easily kicked...Donnie quickly comes to the conclusion that Splinter may have just been going easy on them for the 15 years they've been alive...

Donnie, Mikey, and Raph all try their luck in attacking their incredibly skilled - and now mind-controlled - sensei, but they only find themselves quickly outmatched. Then, Leo duels with him. Splinter knocks the katanas out of his son's hands and prepares to kill him. Just when everything seems completely hopeless, Leo shows Splinter a picture of when he was human (standing alongside his wife, his daughter), along with saying his real, human name. When Donnie and Raph pin Splinter to the ground, Leo calls him "father" for the first time in a long time. The Rat King tells Splinter to not listen to the turtle - That his place in life is with Rat King only. Once again, Splinter prepares to kill Leonardo - but, suddenly, he snaps out of his trance and starts running at The Rat King, whom he defeats within seconds. The turtles all embrace their sensei at once, knowing that his true self is back. All of them watch as the defeated Rat King is carried off by dozens of rats......

Later, Splinter is seen meditating in the lair, when Leo comes in to check on him. Leo declares that, someday, he might even become a greater martial artist than Splinter himself. Splinter replies that he has taught his sons everything that they know - he then quickly grabs Leo's arm and throws him against a wall - before adding that he hasn't taught them everything he knows. The episode concludes with Leo saying, "It's great to have you back, sensei", in a rather sarcastic voice.

Gallery
See: I, Monster (2012 TV series episode) / Gallery 

Trivia

 * The title of this episode is named after the original Rat King appearance in the comics which is in turn a reference to "I, Robot", a collection of short stories written by Isaac Asimov.

Quotes
Leonardo: OK there's the plan: Donnie, you're gonna strike first.

Donatello: No wait. You want me to come at Splinter? I'll get pummeled!

Raphael: Well, getting pummeled is your speciality.

Leonardo: Trust me. It's all in my plan to catch Splinter off guard.

Michelangelo: Don't take this the wrong way Leo, but against Splinter, your plans always get our butts whipped.

Leonardo: OK new thought: Mikey, you attack.

Michelangelo: He took it the wrong way.

Raphael: Enough talk! Let's do this!

More to be added.....