The Foundation finds itself threatened by the mutant known only as The Mule. In a race to save themselves (and the plan) the Foundation turns to its last great psychologist...
Brilliant.
The best book in Asimov's Foundation series because it answers the question who is watching the watchers? One of the biggest mindf&*ks I've ever experienced in a novel.
What is the "opposite end of the galaxy" to a psychologist, anyway? The mule is a cool idea, the weird abbreviated language of the Second Foundationers is also cool.