Athanael can think of only Thais. He is no longer able to control the desire he feels for the woman he converted. When the courtesan appears to him in his dreams, he hears heavenly voices telling of her imminent death. In despair he sets off to visit her.
When Athanael reaches the convent, Thais already lies dying. He confesses his love for her. Suddenly the roles are reversed: Athanael extols Thais’ beauty and recognises earthly love as the only truth; but Thais can only see in him the man who showed her the way to eternal life. After receiving a vision from heaven, he dies in the arms of the distraught Athanael.