The turtles are doing their best to clean up the mess left by the Kraang, this includes clearing out and shutting down abandoned facilities before someone gets hurt.
An unfortunate accident leads to a dramatic life changing opportunity that not everyone is entirely happy with. Now the turtles have to find a way to live with, and accept their new roles in life, while under the watchful eye of someone who no longer has their best interests at heart. If he ever did to begin with.
The world is a lot larger than any of them had previously been aware of, on the run, the turtles find sanctuary in the unlikeliest of places.
Trying to build a life for themselves isn’t easy when they are still faced with so many obstetrical to overcome, and a past that just won’t let them go.