By setting the play in Ephesus (which was known to the Elizabethans by their familiarity with the letters of St Paul) Shakespeare capitalised on that knowledge by taking some of the Apostle's teachings ― slaves being obedient to their masters, wives being faithful and obedient to husbands and, supremely, the avoidance of 'concupiscence' and fornication ― and turns them on their heads. Slaves are obedient ― but to which master? Wives are faithful ― but to which husband? An erring husband discovers that fornication has financial consequences.
Two sets of twins - two masters and their two slaves - cause chaos and create a tangled skein of confusions involving orders, counter-orders, mistaken identities and lust-filled liaisons. Action, reaction, come thick and fast until the Elizabethan love of order brings about resolution via a long-lost wife.