The setting for A Funny Thing Happened on the Way to the Forum is a street in ancient Rome, in front of three adjacent houses. First is the brothel of Lycus, who takes his profession of peddler of fresh very seriously. Next is the house of Senex, his wife Domina, and their son Hero. Last is the house of Erronius who continually bemoans the unsolved kidnapping long ago of his son and daughter.
Pseudolus, a slave in the household Senex and the property of Hero, is anxious to obtain his freedom. To do so, he will resort to all kinds of trickery, abetted reluctantly by fellow-slave Hysterium. (“I live to grovel,” he says complacently.) Pseudolus, who is a conniving and quick-witted rascal, has figured that the best way of bargaining for his freedom is to cater to the sex-hungers of the men of the household, especially Hero, who yearns for the beautiful Philia, a still virginal girl who is in basic training for a courtesan’s career in the bawdy house run by Lycus. Hero agrees to give Pseudolus his freedom if he can help him win Philia.
Hero’s aging father, however, lecherously wants to have a last fling and likewise has his eye on Philia. Thus, Pseudolus must also try to give him what he deserves. Finally, as the ultimate complication, Pseudolus is faced with the contracted fact that Philia has already been sold by Lycus to Miles Gloriosus, a soldier momentarily absent from Rome.
Forced to foil all the males who are after the lovely but dumb Philia, Pseudolus has to maneuver with resourcefulness and agility, and the action crosscuts from the chaste to the chase with dizzying speed. Guffaws keep erupting as the schemes of Pseudolus boomerang and get him ever deeper into a mire of deception, entangling everybody who comes near. When the vainglorious and licentious Miles Gloriosus returns to Rome and demands fulfillment of his contract for Philia, Pseudolus is in desperation and quickly declares that she is dead. To help him in this charade, he persuades Hysterium to don a wig and women’s clothes and pretend to be the corpse.
The very much alive Philia, hearing her contracted owner has returned, dim wittedly thinks that old Senex is the man who has purchased her, so Senex excitedly tries to escape his battle-ax of a wife, Domina, in order to enjoy his good luck. In preparation for the anticipated encounter, he oils himself with sweet ointments and begins issuing a gurgling mating call.
The ever-funny comic bit of mistaken identities kicks into high gear as there are suddenly three Philias: the real one, Hysterium in his fright-wig and women’s clothes, and Domina, who, in a similar wig, is attempting to snatch back her husband in the guise of the young courtesan. Suddenly everybody is chasing everybody else, mistakenly and hilariously, as the wily Pseudolus keeps the three unsuspecting Philias from confronting each other.
In the end it is discovered that the real Philia and Miles Gloriosus are long-lost brother and sister, the kidnapped children of Erronius. Since they are siblings, Miles Gloriosus voids his contract for Philia, and she is found of sufficient high birth to become Hero’s bride. And, of course, the scheming Pseudolus wins his freedom.