The Bagge Family arrives in New York City, as Muriel has won a sitar contest and her prize is to perform at Radio City Music Hall. At the theatre, the family is welcomed by a giant cockroach who calls himself Schwick; his real name is Buschwick, where he's from, but not under any circumstance may anyone call him that. He poses as a stage hand and promises Muriel her own rehearsal room and Eustace hotdogs.
Schwick shows them to the "rehearsal room," a scary, musty room littered with shackles and human remains. There is an unseen threat living in a mouse hole in the room that is responsible for the demise of previous of the theatre's stars. The argumentative Schwick sends Courage out to get a package and orders him to hurry up and to keep the police out of the picture, otherwise "It's curtains for the sitar lady."
Courage tries to find the house where the package is waiting, and eventually finds his way to the block of an condemned apartment. The building's inhabited by several monsters and unseen residents behind sealed doors screaming to be released, such as the mysterious Violin Girl, who scares away Courage with a demonic face so she can practice her violin uninterrupted. After retrieving the package, Courage flees the scary abandoned apartment building and jumps on a subway train. A policeman, who is searching for the "evil" package, has followed Courage and asks him to show his license.
The railroad engineer is so terrified by the sight of the evil package, he flees the train. Courage tries to take control, but unfortunately steers the train into the theatre's rehearsal room, where Muriel is still practicing. Schwick takes the evil package, which contains nothing more than a window squeegee that Schwick needs to wipe away the cry for help written on the grimy window. However, the train collision has broken the squeegee. The bug is infuriated, yells "Nobody double-crosses Schwick!" and now opts to unleash the rehearsal room monster.
Courage panics and carries Muriel as Schwick chases them; they eventually make it up to the Radio City stage, where Muriel performs. The police officer from the train has called for backup, disguised as dancing women in the performance, and Schwick is kicked into a trombone. Schwick turns out to be a wanted fugitive, who is obviously not a real stage hand, and gets arrested.
Muriel finishes her masterpiece to massive applause, and Eustace, having been eaten and reduced to nothing but a skeleton by the unseen monster, is seen watching his wife on TV in the rehearsal room, while complaining about the channels.
- This episode won the "Best Sound Editing — Television Animated Series — Sound at the 2001 Golden Reel Awards."
- When Courage enters the building, one can clearly hear a man shouting "Open the door!"
- King Ghidorah, one of the most famous kaiju in the Godzilla films, was one of the monsters living in the apartment building. This could be a jab at how many Japanese there are living in New York.
- The Weasel from The Demon in the Mattress make a cameo in this episode.
- On Cartoon Network Asia, Cartoon Network Philippines and Cartoon Network Australia, the part with the apartment rooms is cut for fear the Violin Girl may be too disturbing for the show's target audience. This scene is left intact when it reran on Cartoon Network and Boomerang in the United States and its respective feeds in parts of Europe.
- This is probably the most famous episode of the show, along with "King Ramses' Curse" and "Perfect."
- Although Eustace supports briefs over boxers in this episode, he is mostly seen wearing boxers in other episodes.
- The "Briefs! Boxers!" scene has become a popular Internet meme, as has the Violin Girl scene.