Daru is assigned the "official" responsibility to escort a prisoner, an Arab, to the nearby jail. The Arab has been arrested and is to be taken to jail for judgment, sentencing and incarceration.
Daru, who has seen action in war, now lives quietly and peacefully as a teacher on a barren plateau. He will fight for his country, but he refuses to take the Arab to jail. He tells Balducci when the man brings the prisoner to him, but Balducci says his job was to deliver the prisoner and Daru must make his own decision: Balducci will not report him.
Daru isn't quite sure what to do with the Arab, though while the man stays with him, Daru treats him more like a guest than a criminal.
At one point, referring to the quote, "Daru felt a sudden wrath against the man, against all men with their rotten spite, their tireless hates, their blood lust," Daru resents the circumstances that have brought this situation to his door. He resents the fighting of all men, but especially those of his country (France, pitted against the Arabs), and the fact that if the Arab was going to kill someone, why couldn't he be smart enough not to get caught.
Camus wrote this story in response to his refusal to take sides in his own life, in the battle between Algiers and France. He speaks to this through Daru who resents being told he must choose. Ultimately, he does not follow directions, but gives the Arab the means to escape (though the Arab does not do so).