One night, on board a liner returning from Asia, a passenger who never sleeps approaches the narrator and tells him his secret. A doctor at a remote post in the Dutch East Indies, he was visited by a European woman, beautiful and proud, who came to ask him for a forbidden operation.
He refused, out of pride as much as desire, then set off after this woman like a man seized by madness. That is where the title comes from: amok, the frenzy that, in Malaya, drives a man to run straight ahead.
You can read this short story by Stefan Zweig in one sitting in the language you are learning.
