At the end of Foundation, the triumph of Hari Seldon’s Foundation seemed assured. So Asimov decides to throw a wrench into the works with the creation of the misbegotten warlord the Mule. Asimov apparently did this at the insistence of his then editor John Campbell. However it came about, the Mule becomes one of the very best SF characters ever. With his ability to control minds over great distances, he brings the Foundation’s march across the galaxy to a halt (I was going to say screeching halt, but there’s no sound in a vacuum. A fact robustly ignored in SF films. Yes, I’m talking about you, Star Wars) and the book ends with the Mule seemingly in full charge of things. Speaking of cinematic adaptations as I believe I just was, I’ve seen the trailers for the Foundation TV series, and, based on that alone, I’m not seeing much there that I recognize from the books. They appear to have removed everything after the title. I can’t stress enough that if you want to really experience what Asimov intended, you owe it to yourself to read the books.