Ignatius Reilly, a mountainous man in a green hunting cap, waits outside the D. H. Holmes department store for his mother. He is cranky about the waiting.
A policeman, Officer Anthony Mancuso, asks Ignatius for identification, because he thinks Ignatius looks weird and hopes to be able to arrest him.
Ignatius protests loudly that he is waiting for his mother; the crowd takes his side against Mancuso.
Mrs. Reilly returns to Ignatius, and they both blame the disturbance on an old man in the crowd who calls all policemen communists. This is a strategic error on his part.
The policeman arrests the old man, and the Reillys walk rapidly away down Bourbon Street, before entering a seedy strip club/bar called the Night of Joy.
Mrs. Reilly orders drinks. The bartender tries to get them to leave by being rude to them, with no effect.
Ignatius tells a long story that his mother has heard before about a trip he took by bus to Baton Rouge to interview for a job in the Medieval Studies department at the university.
This was the only time Ignatius ever left New Orleans. The trip was traumatic—Ignatius did not get the job, and his favorite jacket was stolen—but now he gets to tell the story over and over again, so that's something.
Meanwhile, at the police station, the old man (named Claude Robichaux) that Mancuso arrested meets Burma Jones. Jones is a black man who was arrested because he was nearby when someone stole a bag of nuts in Woolworths.
The police sergeant bawls Mancuso out for arresting Robichaux for no reason and for trying to arrest Ignatius while his mother was standing right there.
The sergeant tells Mancuso to call Robichaux's daughter to come get him; this will humiliate him and pay him back for calling the police Communists.
Back in the Night of Joy, Ignatius and Mrs. Reilly chat with Darlene, a B-drinker who works there trying to get lonely guys to buy her watered down drinks. They also talk to a gay man (whose name we learn much later is Dorian Greene).
Ignatius tells his story about the bus again to Darlene, who is remarkably patient, and Mrs. Reilly sells her hat to Dorian, who is a dealer in used clothing.
Then she starts eating and sharing the cakes she bought earlier in the day. Darlene likes them, but the bartender remains cranky (especially because the increasingly drunk Mrs. Reilly drops and breaks her beer bottle).
Ignatius and Mrs. Reilly start to argue; Darlene takes Mrs. Reilly's side.
Lana Lee, the owner of the bar, shows up to yell at Darlene for encouraging the Reillys to stick around when anyone can see they're bad for business.
Out of the bar the Reillys go, with Lana Lee shouting good riddance after them.
Ignatius discovers that his mother has sold her hat, and becomes excessively upset about it because he loved that hat.
Finally after much bickering they arrive at the car. They get in and Mrs. Reilly, who is drunk, drives into another car and then into a building.
Masonry falls on them. Ignatius does not take this quietly.
Officer Mancuso, dressed in ballet tights at the insistence of his vengeful sergeant, finds them amidst the ruin.