Gatsby, Nicks neighbor in the big house next door, puts on very big parties every weekend. These affairs seem to operate on an open admission basis. There is always plenty of good food to eat and good liquor to drink. An orchestra plays jazz. The attendees party whole heartedly.
Nick actually receives an invitation to one weekend party, so he puts on white flannels and walks over.
He finds Tom and Daisys friend Jordan Baker, the beautiful golf pro, on the mansions marble steps.
Jordan and Nick explore the party together. Its extravagant. They listen to people talk about their very rich and very mysterious host Gatsby. Everyone has a pet theory about who he is and where he got his money.
Nick is watching the fun. Hes drinking a little champagne. He meets a man his own age, a fellow war veteran. They chat politely. It turns out that this is Gatsby. When Nick apologizes for not realizing it, Gatsby charms him.
He smiled understandingly much more than understandingly... and showed a quality of eternal reassurance concentrated on you which understood you just as far as you wanted to be understood.
Emerging from the spell of Gatsbys smile Nick observes an elegant young rough-neck, a year or two over thirty, whose elaborate formality of speech just missed being absurd.
Gatsby is called to the phone and Nick and Jordan speculate about him a little bit and listen to some jazz.
Then Jordan is called away to talk with Gatsby. When she returns she tells Nick shes heard something amazing.
Nick leaves the party late. He says good by briefly to Gatsby, wades through a good deal of drunkenness in the yard of the mansion, and crosses over to his little house next door.
There is a sort of a coda to Chapter Three in which Nick tells us of his working life in the City, the bond company, his walks around the city at night. We are made to feel his loneliness and romanticism. He tells of Jordan Baker whom he is beginning to see regularly. There is a foreshadowing of a later central plot event: Jordan and Nick are driving home one evening and Jordan nearly hits a pedestrian. When Nick cautions her, she shrugs it off.
Nick is attracted to Jordan but full of interior rules that act like brakes. There is a girl back in the Midwest to whom he has been writing letters. He feels he must break off that relationship before he can enter a new one.
Everyone suspects himself of at lest one of the cardinal virtues, and this is mine: he tells us, I am one of the few honest people I have ever met.