“With my mind control serum coursing through their brains, resistance is futile!” – Stockman

Tiger Claw is making a deal at the docks, but the Mighty Mutanimals are there to stop him. Unfortunately, they are no match for Shredder’s henchman, and Tiger Claw escapes with his prize – and with Slash and Rockwell. Worn out, Leatherhead makes his way to the turtles’ lair and enlists their help in retrieving the captured Mutanimals. Meanwhile, Tiger Claw returns to Shredder with the appropriate chemical for the mind control formula. Baxter Stockman is ordered to test the formula on Slash and Rockwell, and inserts worms into their brains to complete the process.

The remaining Mutanimals and turtles arrive at Shredder’s compound, only to find Slash and Rockwell escaping. Saving their friends, they all return to the lair, yet only Michelangelo recognizes something as amiss. As Slash tries to explain, the worm takes control, causing the mutant turtle to attack. The mutants fight one another, and Slash and Rockwell capture Raphael as Shredder’s new guinea pig. The others hurry after their friends and brother. With the Shellraiser back in operation, the turtles give chase, but Rockwell gives them the slip.

While Stockman inserts a worm in Raph’s brain, the others prepare to attack Shredder’s compound. Infiltration leads them to where their brother is being tested by Shredder. But with Raph completely under Shredder’s control, he is put to work defending his new master. Leonardo goes head-to-head with his brother, but the other mutants are released into the fray as well. Leo manages to keep his brother at bay, then tries to play on Raph’s emotions to remove the worm. Successful, they free Slash and Rockwell as well, and the two mutant teams take the fight to Shredder together.

The ninja master makes quick work of his enemies – until Slash drops a statue on him. With the arrival of the Foot, the mutants escape and return to the lair. However, Shredder still has his formula, and it works, putting everyone in danger.

It’s always a pleasant sight when some of the characters that were created over the last three seasons serve a purpose beyond being the mutant of the week. Even though the Mighty Mutanimals were all familiar faces, there was no guarantee that the team would be seen with any sort of regularity. They could have been reserved for finales, their own occasional stand-alone episode, or TMNT content not on TV. So it’s great to have them appearing for an episode that not only pairs them with the turtles, but also has larger impact on the story. They are being ingrained in the development of this show, as well as the minds and hearts of the audience. Fans now care about these mutants as individuals and as a team, which certainly raises the stakes of what can be done with them in the future.

The idea that Shredder is using mind control on Karai has been met with some skepticism so far, and this episode didn’t help that too much. One thing that made the Karai situation worse was that it seemed like Shredder genuinely cared about her in his own way. With the advent of a mind control formula and the disgusting method for its application, it’s hard to argue that Shredder’s goal is still just to change her back and save her. Instead, it’s becoming more likely that he wants to use her as is, and as long as she obeys him he doesn’t care what form she takes. So whether or not Karai will ever be given her humanity back remains to be seen.

With the recent emphasis placed on the mind control formula and its perfection, it seems likely that something big will be happening soon. However, with a number of episodes remaining before a season finale, it would be more likely that now this whole aspect of the plot is swept under the rug for a while, only to reappear when it comes time for the finale later this year. Perhaps fans will be surprised, but if history is a guide, then this will get dragged out for a while to come.