S. Antipholus is still at the marketplace, waiting for S. Dromio to come tell him about whether any ships are leaving. S. Antipholus wonders at his good luck; it seems everyone in the whole city knows him and is kind to him, though he has no idea who they are. He’s convinced the place is overrun with sorcery, and his mind is being played with.
S. Dromio then arrives with the gold to pay E. Antipholus’s debt, and tries to give it to S. Antipholus. S. Dromio then has to explain to the confused S. Antipholus that he was recently arrested, which one would think a person would remember.
S. Antipholus, however, just wants to know about the ships he asked S. Dromio to look for. He is certain he already told S. Antipholus about a departing ship a long time ago, only to be told to bring money for bail instead. S. Antipholus, rather than investigate the matter further, simply declares the two of them seem insane as they wander in an illusion.
The Courtesan (the conversationalist wench E. Antipholus went to see at the Porpentine) enters, seeming another vision of the devil. Of course she’s familiar with E. Antipholus, but S. Antipholus only recognizes in her the usual courtesanly stuff – gaudy but sweet temptation. S. Antipholus and S. Dromio joke happily about light, which they pun on. They call the Courtesan light, as the devil himself was an angel of light, and they also twist the notion that the woman is light in the Shakespearean sense, meaning "easy." Finally, they decide that she is light like fire, which will burn.
Anyway, the Courtesan talks about the dinner she just had with E. Antipholus, where he took a ring from her worth 40 ducats, and promised her a gold chain in exchange. She notes S. Antipholus wears the chain, but when she asks for it, or her ring back, he runs away.
The Courtesan, out a ring and a customer, decides she’ll go to his wife, which is a dangerous but useful tactic. The Courtesan is sure Antipholus is mad, and she intends to tell Adriana that Antipholus ran into her house and stole her valuable ring.