Lost in a thick forest somewhere in the South of Germany, the storyteller happens on a long-bearded hermit, from whom he asks directions to the nearby village of B——. He is puzzled by the reply, though, for the hermit refers to the forest as a desert and recommends that he follow a friend to Alexandria, which is in Egypt, not Germany.

From a traveler on the road he later learns that the odd fellow is known to the villagers as Priest Serapion, a kindly gentleman who is “not quite right in his head.” Dr. S—— provides more background, explaining that the hermit, once one of the most brilliant men in the town of M——, was about to be sent on a diplomatic mission when he mysteriously disappeared. At nearly the same time a hermit calling himself Priest Serapion suddenly appeared in the vicinity. Then one day Count P—— of M—— recognized him as his lost nephew. Arrested after a violent struggle, he was committed to a lunatic asylum in B——.

The medical men there found only one thing wrong with his mind: the fixed idea that he was the same Serapion who fled the Theban desert in the days of the Emperor Decius (in the third century) and suffered martyrdom in Alexandria. Probably with the help of Dr. S——, he escaped from the asylum and was allowed to live in a hut he built in the forest.

Himself an amateur psychologist, the storyteller decides to go back to the forest and cure Serapion by attacking his fixed idea...

(The entire section is 565 words.)