Changing schools again, the narrator moves to Oxford, where he picks up the vice of gambling. Skilled at this vice, the narrator chooses weak-minded classmates on whom to prey for extravagant monetary gain. After two years at Oxford, the narrator meets a young nobleman named Glendinning and makes him his next gambling target. Allowing him to win at first, the narrator invites him to a large party he has arranged, luring him with the prospect of more success. At this party, Glendinning plays exactly as the narrator expects and quickly amasses large debts. The moment he quadruples his debt, Glendinning becomes ghastly pale, and the narrator realizes his triumph. Suddenly, however, a stranger intrudes on the party with a rush that extinguishes all the candles in the room. He reveals the narrator to be a scam artist and promptly retreats. The announcement ruins the narrator, forcing his departure not only from Oxford, but also from Britain. 

From there, the narrator travels around the European continent, but his schemes are continually foiled by William Wilson. One year in Rome, during the festival of Carnival, the narrator attends a masquerade ball in the palace of the Duke Di Broglio. The narrator secretly desires the wife of the duke, who has informed him of the costume she will be wearing. As he searches for her, the narrator feels a light hand on his arm and hears a whisper in his ear. The whisperer wears the same costume as the narrator, a Spanish cloak with a black silk mask. Drawn into a side room, the narrator becomes enraged, drawing his sword and stabbing his rival. To the narrator’s horror, the layout of the room mysteriously changes, and a mirror replaces the body of his antagonist. He stares into the mirror to find his own body stabbed and bleeding, and he hears his rival speak as though with his own voice: “In me didst thou exist—and, in my death, see by this image, which is thine own, how utterly thou hast murdered thyself.”