He confides to Peniculus, a professional parasite, that he has stolen his wife's mantle and is going to give it to Erotium, a prostitute who lives next door.
He first protests vainly that he hasn't any wife and has just arrived in the city, then begins to realize the possibilities of a dinner and a pretty girl.
Act 3: After the meal, he leaves his house with a garland on his head and the mantle over his arm; Erotium has told him to have it re-trimmed.
He is chuckling over his luck—dinner, kisses and an expensive mantle—all for nothing, when the irate Peniculus, who has lost the Epidamnus twin in the Forum crowd, meets him and berates him for dining before he could arrive.
Quite naturally treated as a stranger, Peniculus angrily rushes to tell the other twin's wife of the stolen mantle.
The Syracuse brother, further baffled because the unknown Peniculus addressed him by his name, is pinching his ear to make sure that he is awake when Erotium's maid comes out and hands him a bracelet to be taken to a goldsmith for repair.
He suspects that something is amiss, and hurries off to the inn to tell Messenio of the happy shower of valuables that has been raining upon him.
Act 4: Now the furious wife, told by Peniculus of her man's trick, rushes out of her house just in time to meet her husband returning from the Forum, expecting Erotium's banquet.
She tells him to return the mantle or stay out of her house, and the husband goes to Erotium to get it, resolving to buy his sweetheart a better one.
So the Epidamnus twin finds the doors of both his wife and mistress slammed in his puzzled face, and goes off to get the counsel of his friends.
The Syracuse twin returns, in his quest of Messenio, at the moment when the servant hurries back with his purse.
His master upbraids him for having been gone so long, but the slave protests that he has just saved his owner from ruffians and has been set free.
The happy master truly sets the slave free, and the brothers decide that the first Menaechmus shall go to live with his twin in Syracuse.
In Plautus's plays the usual pattern is to begin each section with iambic senarii (which were spoken without music), then a scene of music in various metres, and finally a scene in trochaic septenarii, which were apparently recited to the accompaniment of tibiae (a pair of reed pipes).
She is at first welcoming, but when he asks for the cloak back and denies having taken the bracelet she grows angry and refuses to admit him.
[8] Shakespeare's work was in turn adapted for the musical theatre by Rodgers and Hart in The Boys from Syracuse and as the 1954 opera Double-Trouble by Richard Mohaupt (Libretto: Roger Maren).