In two linked narratives, the Foundation faces its greatest threat yet: first from a resurgent Empire led by a capable general, and then from the Mule, a mutant with the psychic power to bend men's emotions, whose rise no amount of psychohistorical prediction could foresee. The second installment of the original trilogy deepens the scope of Asimov's universe with a more personal story at its center. A pivotal entry in which the limits of Seldon's grand plan are exposed.