Major spoilers ahoy!
This post contains major spoilers for everything in the TMNT cartoon series after City at War. You can start with season 2 or with season 4, but I'm warning you that the season 4 stuff might not make sense if you don't know the backstories.
Shredder returned after City at War; Karai went back to serving him, which made Leo kind of bitter, but Shredder raised Karai and she feels her foremost loyalty to him still. There is also apparent tension throughout season 3 between the baddies, as Shredder seems to be favoring Karai over Hun.
Then there was the Battle Nexus championship, a sort of interdimensional prize fight which takes place in the Battle Nexus, which is situated between dimensions. Splinter sneaks off to compete- he had won the championship last time despite the treachery of one Draco. We also meet Usagi Yojimbo here, and it's totally awesome. Remember the Ultimate Ninja? Turns out he's the son of the Daimyo, who runs the Nexus, but he has ambitions and plots with Draco to take revenge on Splinter and the Turtles and wrest control from his father. Over the course of many kickass fight scenes, the Turtles win and the Daimyo's mystic war staff creates some kind of vortex that sucks the two baddies in. I'll also tell you that Mikey wins the tournament, which is not a real spoiler because he himself doesn't shut the fuck up about it for approximately 60 episodes (and counting!). Oh yeah, we also re-meet Traxamus, who has escaped the gladiator pits thanks to the Turtles' distraction and is now raising help for a rebellion against the Triceratons.
Season 3 began with the Triceratons tracing the transmat signal to Earth, where they believe they'll find the Fugitoid. Lots of cool shit happens. We are also introduced to Bishop, a sort of black-ops individual working at his own agency at the US government. He has captured and been experimenting on Leatherhead, and he cuts a deal with the Federation's General Blanque in order to get his hands on the Turtles. Also- Bishop knows how to fight. Really well.
With the help of Splinter and April and Casey (the latter two of whom now dress in black for some reason when on these little missions), the Turtles escape, drive Bishop off, and free the Fugitoid. The Fugitoid manages to infect both fleets with a virus that disables their weapons systems, so the war has to stop. The warring leaders are captured and Traxamus takes over; he has been hiding out in the homeworlds leading the rebellion and helps the Turtles during this story arc. Fugitoid, alas, sacrifices himself to finish transmitting his virus.
There are various skirmishes with Shredder throughout the season; the invasion of the Triceratons left a lot of alien tech lying around, and Shredder is now paying for a lot of the cleanup, playing up his role as a humanitarian friend of the city while secretly nabbing the tech for himself. Worth noting with Karai is the end of one ep where she is sent after the Turtles when a set of robots fails to kill them. She looks at the Turtles and then tells Shredder they're long gone. Who knows what that means.
We see Bishop again in Hun on the Run, where he captures Karai and uses her to force Shredder to give up alien tech to him. Hun, in extreme disfavor now, is sent to retrieve Karai, and Baxter tries to sabotage him by sending the Turtles a false transmission that Hun is looking for a weapon to defeat them. The Turtles rescue Karai- Leo's idea, naturally. :D There is a totally awesome fight scene with Karai, Hun, and the Turtles fighting Bishop. Sadly this ep is not scheduled for dvd release. (I HATE YOU FUNIMATION.) Anyway, Bishop has to run again.
Now we have a story arc where we meet Renet. Yay! The episode is changed from the comic in that the villain isn't Savanti Romero (and of course Cerebus is gone, for legal reasons, woes), it's an Ultimate Ninja/Draco monster- the two fused when sucked through the vortex. They manage to get away with the time sceptre, but Lord Simultaneous returns the Turtles home. Ultimate Draco takes his revenge by casting the Turtles into different dimensions, and we have one ep solidly devoted to each- Mike goes to an alternate where the Turtles are superheroes, Raph goes to the Planet Racers continuity, Don is sent to an alternate where Shredder has conquered the world, and Leo goes to Usagi's world. After various adventures, the Ultimate whosit is defeated, seperated and both villains turned to dust. Lord Simultaneous shows up to reclaim his sceptre and uses it to return the Ultimate Ninja to young boyhood, to comfort his father.
Bishop returns again in another one-shot, more fighting, etc. The season ends with Exodos- Splinter receives a vision of his Master Yoshi, warning him about Shredder. After investigation, the Turtles find that the Shredder has a spaceship built from alien tech and is preparing to leave Earth, so he can go to the Utrom homeworld and destroy it, then spread terror across the universe, whee. There's lots of fighting and lots of biplay between Leo and Karai- Leo is pissed at Karai for helping an honorless bastard like Shredder, but she's frankly pretty naive and just does not understand what he is all about. You totally need to blow the $15 for "Shredder's Final Countdown" because the fight scenes in the Exodus arc totally and completely kick ass. Also I forget at what point in the series this happened, but Fugitoid returned- turns out he uploaded himself to...somewhere...before he "died" and had been trying to download himself to Don's little palm pilot thing- Don's been getting weird fax noises on the shell cell all season, so it was foreshadowed.
Part two! More fighting- basically they really kick the shit out of all 4 Turtles and Splinter. Like, seriously. Also, Karai totally stabbed Leo, which made many fangirls froth with rage but amused me tremendously. Now I'm fuzzy cuz it's been a while since I've seen this, but I believe the only solution to this mess was to destroy the ship- which would necessitate the Turtles dying too. They decided to do it, to save the universe from Shredder, which was really pretty heroic. Also, Leo called Splinter "father" which was enough to make you cry.
The Turtles were saved when Utroms beamed everybody out of the ship- they put Shredder on trial and sentence him to exile on a remote planet, which is presumably the last we'll see of him. (They managed to get him to the planet without crashing the ship this time.) Karai is in custody and the Turtles are alive but broken...that's where the season ends.
Season 4 is where they changed the theme song, to reflect Shredder's departure and the rise of Bishop as a more prominent villain. I was mad at first but I'm happy now- the new animation is definitely awesome, although Mikey still needs a good shove off that damn ledge he's dancing on. Season 4 starts with the Turtles at the farm in Northampton, presumably rehabilitating- they're still quite bandaged. This is where we first see Angry!Leo. He is about 50 different kinds of sexy- he talks in this really deep growly voice, and he's REALLY simmering all the time, and he beats the shit out of people. Raph is all like, "Wow, now he's like me." It's funny AND sexy. (We find out after a coupla eps that the reason he is all upset is because he feels like he failed his family, because the only way for them to win in Exodus was to sacrifice themselves. So he's more dedicated to protecting them. And as you see from him backtalking Splinter in this new ep, he has his own ideas of how to do that.)
This season we also meet the Atalanteans, an ancient race of literary devices that created two slave races- the mer-people we see in "Sons of the Silent Age" (which the cartoon totally ruined, but never mind) and the avians we see in "Wing and a Prayer," which was a stupid episode. Not that I'm opinionated! "Dragon's Brew" described the rise of Hun and his Purple Dragons now that Shredder is gone. Looks like he'll be a new big villain too. "I, Monster" has the Rat King, who I think we'll see again- we've already seen him once, he's the "Slayer" that Bishop created using Splinter's DNA on an ordinary human back in season 3. Really, this season so far is all about the monsters.
The only other plot continuity things are "Grudge Match"- where Mikey goes back to the Battle Nexus for a rematch against Kluh, his final tournament opponent who he defeated pretty much by accident. Except then Kluh decides to cheat and kill Mikey, so they had to let him win. Bah! I wanted him to shut up about being the champion. (Continuity note: Wing and a Prayer actually comes after Grudge Match- the order was shuffled for some reason.) The other continuity ep is "Bad Day," which of course you saw- now you should be about where we are, seeing that Karai is back and wants revenge.
Hooray! I love this show so much that I can't even explain it. I just sit there with a big stupid grin on my face for every episode.
Shredder returned after City at War; Karai went back to serving him, which made Leo kind of bitter, but Shredder raised Karai and she feels her foremost loyalty to him still. There is also apparent tension throughout season 3 between the baddies, as Shredder seems to be favoring Karai over Hun.
Then there was the Battle Nexus championship, a sort of interdimensional prize fight which takes place in the Battle Nexus, which is situated between dimensions. Splinter sneaks off to compete- he had won the championship last time despite the treachery of one Draco. We also meet Usagi Yojimbo here, and it's totally awesome. Remember the Ultimate Ninja? Turns out he's the son of the Daimyo, who runs the Nexus, but he has ambitions and plots with Draco to take revenge on Splinter and the Turtles and wrest control from his father. Over the course of many kickass fight scenes, the Turtles win and the Daimyo's mystic war staff creates some kind of vortex that sucks the two baddies in. I'll also tell you that Mikey wins the tournament, which is not a real spoiler because he himself doesn't shut the fuck up about it for approximately 60 episodes (and counting!). Oh yeah, we also re-meet Traxamus, who has escaped the gladiator pits thanks to the Turtles' distraction and is now raising help for a rebellion against the Triceratons.
Season 3 began with the Triceratons tracing the transmat signal to Earth, where they believe they'll find the Fugitoid. Lots of cool shit happens. We are also introduced to Bishop, a sort of black-ops individual working at his own agency at the US government. He has captured and been experimenting on Leatherhead, and he cuts a deal with the Federation's General Blanque in order to get his hands on the Turtles. Also- Bishop knows how to fight. Really well.
With the help of Splinter and April and Casey (the latter two of whom now dress in black for some reason when on these little missions), the Turtles escape, drive Bishop off, and free the Fugitoid. The Fugitoid manages to infect both fleets with a virus that disables their weapons systems, so the war has to stop. The warring leaders are captured and Traxamus takes over; he has been hiding out in the homeworlds leading the rebellion and helps the Turtles during this story arc. Fugitoid, alas, sacrifices himself to finish transmitting his virus.
There are various skirmishes with Shredder throughout the season; the invasion of the Triceratons left a lot of alien tech lying around, and Shredder is now paying for a lot of the cleanup, playing up his role as a humanitarian friend of the city while secretly nabbing the tech for himself. Worth noting with Karai is the end of one ep where she is sent after the Turtles when a set of robots fails to kill them. She looks at the Turtles and then tells Shredder they're long gone. Who knows what that means.
We see Bishop again in Hun on the Run, where he captures Karai and uses her to force Shredder to give up alien tech to him. Hun, in extreme disfavor now, is sent to retrieve Karai, and Baxter tries to sabotage him by sending the Turtles a false transmission that Hun is looking for a weapon to defeat them. The Turtles rescue Karai- Leo's idea, naturally. :D There is a totally awesome fight scene with Karai, Hun, and the Turtles fighting Bishop. Sadly this ep is not scheduled for dvd release. (I HATE YOU FUNIMATION.) Anyway, Bishop has to run again.
Now we have a story arc where we meet Renet. Yay! The episode is changed from the comic in that the villain isn't Savanti Romero (and of course Cerebus is gone, for legal reasons, woes), it's an Ultimate Ninja/Draco monster- the two fused when sucked through the vortex. They manage to get away with the time sceptre, but Lord Simultaneous returns the Turtles home. Ultimate Draco takes his revenge by casting the Turtles into different dimensions, and we have one ep solidly devoted to each- Mike goes to an alternate where the Turtles are superheroes, Raph goes to the Planet Racers continuity, Don is sent to an alternate where Shredder has conquered the world, and Leo goes to Usagi's world. After various adventures, the Ultimate whosit is defeated, seperated and both villains turned to dust. Lord Simultaneous shows up to reclaim his sceptre and uses it to return the Ultimate Ninja to young boyhood, to comfort his father.
Bishop returns again in another one-shot, more fighting, etc. The season ends with Exodos- Splinter receives a vision of his Master Yoshi, warning him about Shredder. After investigation, the Turtles find that the Shredder has a spaceship built from alien tech and is preparing to leave Earth, so he can go to the Utrom homeworld and destroy it, then spread terror across the universe, whee. There's lots of fighting and lots of biplay between Leo and Karai- Leo is pissed at Karai for helping an honorless bastard like Shredder, but she's frankly pretty naive and just does not understand what he is all about. You totally need to blow the $15 for "Shredder's Final Countdown" because the fight scenes in the Exodus arc totally and completely kick ass. Also I forget at what point in the series this happened, but Fugitoid returned- turns out he uploaded himself to...somewhere...before he "died" and had been trying to download himself to Don's little palm pilot thing- Don's been getting weird fax noises on the shell cell all season, so it was foreshadowed.
Part two! More fighting- basically they really kick the shit out of all 4 Turtles and Splinter. Like, seriously. Also, Karai totally stabbed Leo, which made many fangirls froth with rage but amused me tremendously. Now I'm fuzzy cuz it's been a while since I've seen this, but I believe the only solution to this mess was to destroy the ship- which would necessitate the Turtles dying too. They decided to do it, to save the universe from Shredder, which was really pretty heroic. Also, Leo called Splinter "father" which was enough to make you cry.
The Turtles were saved when Utroms beamed everybody out of the ship- they put Shredder on trial and sentence him to exile on a remote planet, which is presumably the last we'll see of him. (They managed to get him to the planet without crashing the ship this time.) Karai is in custody and the Turtles are alive but broken...that's where the season ends.
Season 4 is where they changed the theme song, to reflect Shredder's departure and the rise of Bishop as a more prominent villain. I was mad at first but I'm happy now- the new animation is definitely awesome, although Mikey still needs a good shove off that damn ledge he's dancing on. Season 4 starts with the Turtles at the farm in Northampton, presumably rehabilitating- they're still quite bandaged. This is where we first see Angry!Leo. He is about 50 different kinds of sexy- he talks in this really deep growly voice, and he's REALLY simmering all the time, and he beats the shit out of people. Raph is all like, "Wow, now he's like me." It's funny AND sexy. (We find out after a coupla eps that the reason he is all upset is because he feels like he failed his family, because the only way for them to win in Exodus was to sacrifice themselves. So he's more dedicated to protecting them. And as you see from him backtalking Splinter in this new ep, he has his own ideas of how to do that.)
This season we also meet the Atalanteans, an ancient race of literary devices that created two slave races- the mer-people we see in "Sons of the Silent Age" (which the cartoon totally ruined, but never mind) and the avians we see in "Wing and a Prayer," which was a stupid episode. Not that I'm opinionated! "Dragon's Brew" described the rise of Hun and his Purple Dragons now that Shredder is gone. Looks like he'll be a new big villain too. "I, Monster" has the Rat King, who I think we'll see again- we've already seen him once, he's the "Slayer" that Bishop created using Splinter's DNA on an ordinary human back in season 3. Really, this season so far is all about the monsters.
The only other plot continuity things are "Grudge Match"- where Mikey goes back to the Battle Nexus for a rematch against Kluh, his final tournament opponent who he defeated pretty much by accident. Except then Kluh decides to cheat and kill Mikey, so they had to let him win. Bah! I wanted him to shut up about being the champion. (Continuity note: Wing and a Prayer actually comes after Grudge Match- the order was shuffled for some reason.) The other continuity ep is "Bad Day," which of course you saw- now you should be about where we are, seeing that Karai is back and wants revenge.
Hooray! I love this show so much that I can't even explain it. I just sit there with a big stupid grin on my face for every episode.