In the story, an Irishman, now living near Tacuarembó in Uruguay, recounts his experiences in the Irish War of Independence and how he received the large scar on his face.
[1] Borges starts the story narrating as himself as he is forced to stop in a small town run by the unnamed Irishman, who is known as strict but fair.
His story is as follows: The Irishman describes the war and the introduction of a new comrade, John Vincent Moon, into their band of rebels.
The Irishman recounts how he chased Moon, cornered him and marked a moon-shaped scar on his forehead just before the police captured him.
Then he proceeds to reveal that Moon fled with "Judas' money" while his comrade (apparently) was killed.