Second foundation
(Book)

Foundation series #3 numeration from Goodreads.com.

Foundation series #5 numeration from Fantastic Fiction.

Originally published: New York : Doubleday, 1953.

After years of struggle, the Foundation lies in ruins - destroyed by the mutant mind power of the Mule. But is has been rumored that there is a Second Foundation hidden somewhere at the end of the Galaxy, established as insurance to preserve the knowledge of mankind through the long centuries of barbarism. The Mule failed to find it the first time - but now he is certain he know where it is. And this time the annihilation will be total: no trace of humanity's shining past - or its future hope - will remain. The fate of the Foundation rests on young Areadia Darell, only fourteen years old and burdened with a terrible secret. Is she the Foundation's savior - or its deadliest enemy? A warrior of humanity's light - or a weapon whose every thought and action could be turned against them in an instant? Now, as its scientists gird for a final showdown with the Mule, the survivors of the First Foundation begin their desperate search across the Galaxy in a race against the alien entity. They, too, want it destroyed... before it destroys them.