A merchant of Syracuse, Egeon, suffered a shipwreck some years ago in which he was separated from his wife, Emilia, from one of his twin sons, later Antipholus of Ephesus, and the son's slave, Dromio of Ephesus. The other slave's twin, Dromio of Syracuse and Egeon's remaining son, Antipholus of Syracuse, remained with Egeon. When he came of age, Antipholus of Syracuse was allowed to go in search of his lost brother. After a period of time, Egeon then set out after his remaining son, and the play begins as we learn of Egeon's capture and his condemnation to death by Duke Solinus in the hostile city of Ephesus. The details of Egeon's story move Solinus to pity, and he grants a reprieve until nightfall, by which time a ransom of a thousand marks must be raised.
The twists of plot arise when Antipholus of Syracuse arrives with his slave in Ephesus, where Antipholus's twin brother, together with his wife Adriana and their twin slave reside. Confusion mounts upon confusion: Antipholus of Syracuse abuses Dromio of Ephesus for nagging him to go home for dinner; Adriana locks her real husband out of their home because she takes the Syracusan twin for the Ephesian: it is the other Dromio's turn now to be beaten; Antipholus of Ephesus refuses to pay for a gold chain he had ordered (it was delivered to his brother) and so is arrested. As the situation grows more and more bewildering with everyone certain that everyone else is totally mad, the moment for Egeon's execution is quickly approaching. Antipholus of Ephesus demands that the Duke intercede for him. Egeon sees his son as a last minute savior, but is of course not recognized by him. In the end, the Syracusan twins emerge from an abbey where they had taken refuge, and the complications are resolved. The Abbess, who turns out to be Egeon's long-lost wife Emilia, invites them all at the end to discuss this "one day's error" and "make full satisfaction."