Egeon's son, Antipholus of Syracuse, is also in Ephesus, although neither he nor his father is aware of the other's presence. A friendly Merchant warns Antipholus about the law concerning Syracusans and advises him to pretend to be from another city in order to avoid arrest. Antipholus thanks him and sends his servant, Dromio of Syracuse, to the Centaur Inn with their money (a thousand gold marks) and luggage. Left alone, he muses on his unhappiness, caused by his fruitless quest for his brother and mother. Unknown to anyone, however, his missing brother is actually a prosperous citizen of Ephesus, served by his own Dromio of Ephesus. Antipholus of Ephesus is married to a woman named Adriana, and he is a great favorite of Duke Solinus.
As Antipholus of Syracuse muses, Dromio of Ephesus appears and demands that his "master" come home to dinner. He has mistaken this Antipholus for Antipholus of Ephesus, and Antipholus S., in turn, mistakes this Dromio for his own servant. Their misunderstanding leads to an argument--Dromio E. insists that Antipholus S. return to their house because his wife is impatient with him, while Antipholus S. demands to know what has become of their money and belongings. Eventually, the master slaps the slave, and Dromio E. flees, leaving his master to remark that Ephesus is reportedly full of sorcerers and that one must have bewitched his man. Fearing for the safety of his possessions, he hurries off in the direction of the Centaur Inn.
The scene now shifts to a conversation between Adriana, the wife of Antipholus of Ephesus, and her sister Luciana. Adriana is anxiously awaiting the return of her husband--and his slave, who she sent out after him. Luciana rebukes her for being impatient, saying that a dutiful wife should be a docile servant to her husband. Adriana retorts that Luciana speaks without experience--that once she is married, she will have a different point of view. As they debate, Dromio of Ephesus returns and reports the bizarre behavior of his master (or rather, the man he mistook for his master), saying that Antipholus is mad and will talk of nothing but his gold. Furious, Adriana threatens to beat him unless he brings her husband back, and Dromio reluctantly goes out again. Once he is gone, Adriana tells her sister that Antipholus must have taken a lover--that is the only explanation for his absence and peculiar behavior.
Antipholus of Syracuse is a stronger, more interesting character than his brother, if only because Shakespeare allows him emotions larger than the confusion and anger that Antipholus of Ephesus expresses. Here, we see Antipholus S. experiencing a kind of angst or spiritual incompleteness brought on by the absence of his twin and mother--"I to the world am like a drop of water," he says, "that in the ocean seeks another drop, / Who falling there to find his fellow forth, / Unseen, inquisitive, confounds himself. / So I, to find a mother and a brother, / In quest of them, unhappy, lose myself"(I.ii.35-40). His sense of alienation and loss of self will only increase as the play continues, and he begins to doubt his own identity amid the confusion.
The violence between master and slave when Antipholus strikes his brother's Dromio, believing him to be his own slave, establishes a pattern for the play, as both Dromios (but especially Dromio of Ephesus) complain of the heavy hands of the master--and mistress, since Adriana also is not averse to slapping Dromio around. These beatings are usually played for laughs, however, and it is significant that in a play filled with ropes, drawn swords, and threats no one really gets hurt.
Meanwhile, the description that Antipholus gives of Ephesus as "a town full of cozenage: / As nimble jugglers that deceive the eye, / Dark-working sorcerers that change the mind, / soul-killing witches that deform the body / ...And many such-like liberties of sin"(I.ii.97-102), would have resonated with an Elizabethan audience well-versed in the Bible; in the New Testament, the apostle Paul travels to Ephesus and finds the city full of witchcraft. This theme of enchantment, which, far from being benign, is directly associated with "sin," will be returned to throughout the play, since magic seems to be the only sensible explanation for the peculiar events.
I have written my own act wise summary of comedy of errors. Hope it will help students like me.