After not seeing Gatsby for a period of time, Nick drops by unannounced one Sunday afternoon. Shortly after Nick's arrival, Tom Buchanan and two others, Mr. Sloane and an unnamed young woman, come to the mansion on the horses they had been out riding. Gatsby had previously met the woman, and is aware of the fact that Tom is married to Daisy. Nick finds himself caught in the uncomfortable position of being an onlooker as Gatsby tries to be a gracious host while also trying to size up the man who is Daisy's husband.
He was profoundly affected by the fact that Tom was there. But he would be uneasy anyhow until he had given them something, realizing in a vague way that that was all they came for.
Nick is left making excuses for Gatsby when Tom reacts to Gatsby's inability to recognize an invitation to join the trio for dinner is not sincere.