Having travelled to the past, the Turtles and Renet battle with Savanti Romero and his telepathically controlled dinosaurs as Savanti attempts to change the historic timeline by preventing the dinosaur extinction event.

With Donatello sick the Turtles are desperate. So desperate that they decide to try and sneak into Bishops facility, where they realize they have to make a deal with the devil if they want to cure Donatello

To cure Donatello the Turtles made a deal with the devil aka Bishop. Now they have to retrive a pendant that is supposed to help Bishop in his research. The thing is that the pendant is in the heart of the Foot-building, and Karai won't just hand it over