While the Simpson family visits a museum exhibit on Ancient Rome, Marge chastises a bored Homer for his lack of ambition when he admits to shirking chances for promotion.

The curator overhears their argument and begins to relay the tale of Obeseus the Wide (played by Homer), the son of a poor farmer.

Marjora gives birth to their twin children, Bartigula and Lisandra (played by Bart and Lisa), and Gordus gives Obeseus control of his laundry business and his former slave friends as a wedding present.

When the ambitious Marjora tells him to get his act together, Obeseus' slave friends suggest gathering ammonia (used in the cleaning process) by placing pots near drinking establishments.

Seeing the crisis that plagued Rome, Marjora tells Obeseus to kill Emperor Montimus to gain more power by poisoning him and proposes Bartigula to claim the throne.

After he is crowned emperor, Bartigula the Jerk declares war on Neptune, builds a massive wall across Rome, and dissolves the Senate (by dousing its members with acid).

As Bartigula goes mad with power and declares himself a god, Obeseus is sentenced to be eaten by the lions, only to challenge his son to a gladiatorial battle.

Back in the present, the Simpson family argues about the moral of the tale, and the curator laments letting stupid people into museums.

Minerva complains that the argument has declined in quality, but Jupiter states that he wants to watch it to the end because he has already invested so much time in it, and "it feels like they're wrapping it up".