Early one morning at Mario Brothers Plumbing, Mario and Luigi are asleep on separate ends of the couch; their snoring is pushing a vase back and forth across a nearby counter. Suddenly, the voice of an opera singer can be heard coming through the garbage chute, which in turn wakes up Mario and Luigi. Luigi questions as to what the sound might be, and Mario suggests a catfight. As the singing continues, the singer raises her voice and shatters a window upon striking a high note. Mario then recognizes the voice as that of Mrs. Gammliss, a would-be opera singer living in apartment 5C.
As Mrs. Gammliss continues with her off-key singing, Mario begins to panic about having to keep listening to her sing the entire opera, and asks Luigi as to what they should do. Luigi suggests that they should pray for intermission, but upon realizing that they have no choice but to keep listening to Mrs. Gammliss' horrendous singing, Luigi plugs his ears with his fingers.
At some point, Mario and Luigi put on earmuffs to shield themselves from Mrs. Gammliss' singing. Luigi then attempts to unclog a toilet by removing a plumber's slinky that had gotten stuck in the tank, but assures Mario that he isn't quite finished. Reaching into the tank again, Luigi pulls out a dead fish, and laughs about how some people wonder why their toilets won't work after flushing bizarre objects.
Mrs. Gammliss' voice comes barreling down the garbage chute yet again, much to the displeasure of Mario, Luigi and the Ratigator. Fed up with Mrs. Gammliss' singing, Mario calls up to her through the garbage chute. Mrs. Gammliss then responds to Mario by singing, and he tells her to sing quieter, as he and Luigi can't stand it. She apologizes, but goes on to explain that she needs to practice her singing, and accidentally shatters a glass that Luigi had been holding in the process. For breaking his glass, Luigi tells Mario to pick up some paper cups, and vows to kill Mrs. Gammliss.
Mario then comes up with an idea, and explains that if it doesn't work, they'll have to move. Luigi asks if Australia is far enough, just as Mrs. Gammliss starts singing again. Singing in an operatic voice, Mario tells Mrs. Gamliss to stop practicing, explaining that their brains have turned to oatmeal, and that their ears are ringing. Mrs. Gammliss acknowledges Mario's qualms, and retorts that he'll get shot in his leg. Mario and Luigi then decide to sing several high notes up to Mrs. Gammliss, which results in a crash coming from her apartment.
Speaking in a normal tone of voice, Mrs. Gammliss begs Mario and Luigi to stop, as their singing is destroying her apartment. They tell Mrs. Gammliss that they'll stop singing if she agrees to stop as well, and manage to reach an agreement. Stepping away from the garbage chute, Mario and Luigi take a bow at each other, then have a good laugh about how they consider their own singing to be the kind of opera they'd enjoy, and that Mama would be proud.