by Isaac Asimov, 1953
First half: The 2nd Foundation defeats the Mule
Second half: The First Foundation thinks they defeated the 2nd Foundation – Arkady was programmed on Trantor as a baby so her encephelograph didn’t show she was controlled so her Dad, Dr. Darrell, didn’t think she was. But in reality, the 2nd Foundation planned it all – so the First Foundation would go back on Seldon Plan.