Summary
Antipholus S. muses on the strangeness of the fact that everyone in Ephesus seems to know him: they thank him for favors, show him silk he has ordered, and so forth. Dromio S. arrives with the gold that Adriana has sent to save her husband from prison. Antipholus S. does not understand why Dromio S. has brought him money, since it is the other Antipholus who has been arrested. He asks Dromio S. whether any ships are sailing tonight. Dromio S. replies that he already told him that a ship is leaving soon, and again tries to give his master the money he was ordered to bring. Antipholus S. thinks his servant has been driven mad by the strange atmosphere of Ephesus.

The Courtesan enters and asks Antipholus S. for the chain he promised her, not realizing that it is the other Antipholus who made this promise. Antipholus S. thinks she is either the devil or a witch and orders her to leave. She asks him for the ring he (actually Antipholus E.) borrowed from her at dinner. Antipholus S., who is afraid of her supernatural powers, flees. Left alone, the Courtesan reflects that he is mad. She says that he has promised her the gold chain in exchange for her ring, but now he will give her neither. Also, he told her at dinner that Adriana had locked him out of his house, and concludes that she did this because he is a lunatic. The Courtesan now intends to complain to Adriana that Antipholus has stolen her ring in a fit of madness, and demand repayment.

Analysis
Antipholus S. is increasingly frightened by what he believes to be the culture of witchcraft and sorcery in Ephesus, to such an extent that he only wishes to leave. He is beginning to doubt his own, as well as his servant's, sanity ("The fellow is distract, and so am I, / And here we wander in illusions - /Some blessed power deliver us from hence!" - lines 40-42). Indeed, his rather hysterical reaction to the Courtesan, branding her a witch or a devil in spite of her reasonable demeanor, suggests that he is close to the brink of losing his reason.