Part 1: The Excursions of Mr. Brouček to the Moon
Scene 1
Mr. Matěj Brouček is a rather unkempt drunken landlord in late 19th-century Prague. On a moonlit night in 1888, Mr. Brouček stumbles down Vikárka street after a drinking binge at the Hradčany tavern. In his impaired state, he encounters Málinka. She is upset and dramatically suicidal after discovering that her lover, Mazál (who happens to be one of Brouček's tenants) has been cheating on her. In an ill-advised attempt to calm Málinka, Brouček agrees to marry her. He quickly realizes the error in this and retracts his offer, leaving Málinka to return to her bohemian lover. Brouček decides he has had enough of this stress and dreams of a more relaxed life on the Moon.

Scene 2
Brouček is quickly disillusioned by what he finds in his lunar paradise. He "lands" in the middle of an avant-garde colony of lunar artists and intellectuals, whom the uncultured Brouček clearly despises. He finds himself in the home of an avant-garde artist, Blankytny (a parallel character to Mazál). Blankytny sings a heartfelt ode of platonic love to the lunar maiden, Etherea. This signals the arrival of Etherea and her ‘sisters’ who commence with a song preaching the benefits of a healthy lifestyle. Ironically, Brouček catches the eye of the maiden, who becomes instantly infatuated with the exotic stranger. She whisks him away aboard mythical Pegasus, leaving behind Blankytny in disbelief and despair.

Scene 3
Etherea and Brouček land in the Lunar Temple of the Arts, where a group of inhabitants has gathered. They are immediately startled and frightened at the sight of Brouček, but soon see him as the latest vogue. The locals proceed to present Brouček with the latest in lunar art and treat him to a "meal" of sniffing flowers. Brouček is not at all pleased with this display of art, nor is he nourished by the fragrances. He is soon caught sneaking a bite of pork sausage; the crowd quickly turns on him, and he is forced into a furious escape aboard Pegasus. As he flees, the lunar artists sing praises to art.

Scene 4
As the Moon scene transforms back into the tavern courtyard in Prague, Mazál and Málinka are returning home, and the artists are enjoying a final drink. A young waiter laughs at the drunken Brouček who is being carried off in a barrel. Málinka is apparently recovered from her turmoil, as she and Mazál sing a duet of their love for each other.

Part 2: The Excursions of Mr. Brouček to the 15th Century
Scene 1
Set in the Castle of Wenceslas IV, Mr. Brouček and his fellow drinkers debate the particulars of the medieval tunnels that were believed to exist beneath the city of Prague. Once again, an inebriated Brouček staggers toward his home and is interrupted. He finds himself somehow in one of these dark tunnels, where he encounters apparitions from the past. One of these ghostly figures is Svatopluk Čech, the author of the Brouček stories and a famous Czech poet. Čech expresses his regret over the decline of moral values in the Czech nation. He sings about the loss of true heroes and yearns for a rebirth of his nation. Ironically, Čech's lament is directed toward Brouček himself and toward the satirical nature of this very opera.

Scene 2
Mr. Brouček is transported back in time and finds himself in the Old Town Square in 1420. This is a tumultuous period in 15th-century Prague, when the Czech people, led by Jan Žižka, were under siege by the German armies of the Holy Roman Empire. Brouček is quickly confronted by Hussite rebels, who accuse him of being a German spy, due to his poor Czech grammar laden with German expressions. Brouček somehow convinces the rebels that he is on their side and is allowed to join them.

Scene 3
Brouček is brought to the house of Domšik, a sacristan, and his daughter Kunka. Brouček now finds himself in the midst of an impending battle for the future of the Czech nation, signified by the powerful singing of battle hymns by the gathered masses. The rebels ask Brouček to assist in the defense of Prague, to which he is characteristically averse. As the battle begins, our hero flees the scene.

Scene 4
In Old Town Square, the people of Prague celebrate their hard-fought victory but lament the death of Domšik. Brouček is found in hiding and accused of treason. He is appropriately sentenced to death by burning...in a beer barrel.

Scene 5
Back in 1888 Prague, just outside the Vikárka Inn (Home of the Hradčany Tavern), Mr. Würfl, the landlord of the Inn and the maker of the infamous pork sausage from the Moon, hears moans coming from the cellar. He discovers Mr. Brouček in a beer barrel, visibly relieved to be alive and back home. Our shameless hero boasts to Würfl that he single-handedly liberated the city of Prague.