Summary
Luciana is chiding Antipholus S., whom she believes to be her sister's husband, for wooing her. If he must be unfaithful to Adriana, she says, he should at least pretend he still loves her, be discreet about his affairs, and avoid hurting her. Antipholus S. denies that he is Adriana's husband and declares his interest in Luciana. Luciana runs off in distress to find her sister.

Dromio S. enters, running away from the kitchen maid, Nell (also called Luce - a mistake by Shakespeare), who is romantically involved with Dromio E. and has mistaken Dromio S. for her husband. He gives his master an unflattering description of her as a fat and sweaty woman, and they laugh together at her expense. Nell was able to describe certain concealed distinguishing marks on Dromio S.'s body, which makes him think she is a witch (he must have the same marks as his twin).

Antipholus S., unnerved by the fact that everyone in Ephesus appears to know them but that they know no one, concludes that the place is full of witches. He therefore means to leave before nightfall, and asks Dromio S. to go to the harbor to see whether there is a suitable boat for them to take. He confirms that he is repulsed by Adriana, who believes him to be her husband, but attracted to Luciana. However, he trusts nothing and nobody here, so he is resolved to leave her.

Angelo brings the chain to Antipholus S., believing him to be Antipholus E. Antipholus S. is baffled, saying he never ordered it. Angelo insists that he did, and says he will come to collect his payment at supper-time. Antipholus S. is pleased with his gift and again voices his intention to leave as soon as possible.

Analysis
Luciana makes her second speech about right and wrong behavior in marriage. She assumes that men will have affairs but believes that they should behave discreetly and tactfully, pretending to love their wives. This has an ironic undercurrent of self-sabotage, since we know that Antipholus is wooing her for herself, and before they have even started their relationship, she is giving him license to stray.

Dromio S.'s panic-stricken question to his master, "Am I your man? Am I myself?" and his own reply, "I am an ass, I am a woman's man, and beside myself" (lines 74-76) highlight the theme of identity in relation to others. Dromio S. has suddenly become the property of a woman he does not know, and this makes him wonder whether he is still himself or has mysteriously been transformed. His comic horror-struck bafflement contrasts with Antipholus S.'s romantic invitation to Luciana to "create [him] new" and "transform" him through love (lines 39-40). His promised submission to her ("teach me, dear creature, how to think and speak - line 33)" reverses Luciana's notions of how a dutiful wife should act. Antipholus S. has failed to complete his identity by finding his brother, but he is asking Luciana to create an identity for him.

Antipholus S. benefits from the mistaken identities, as he gains a wife (albeit one he does not want), a potential lover in Luciana, and now, a gold chain. Antipholus E., on the other hand, loses his wife, access to his home, and the chain. This may explain why Antipholus S. is better-tempered, but it could equally be argued that Antipholus S.'s freer spirit makes him more open to new experiences and nature's bounty.