In Chapter Two of F. Scott Fitzgerald’s The Great Gatsby, Tom Buchanan, for reasons unfathomable to Nick, wants to introduce Nick to his mistress, the fact and identity of, Nick points out, was a barely-concealed secret. As Nick describes the situation,
“The fact that he [Tom] had one [a mistress] was insisted upon wherever he was known. His acquaintances resented the fact that he turned up in popular restaurants with her and, leaving her at a table, sauntered about, chatting with whomsoever he knew. Though I was curious to see her I had no desire to meet her—but I did. I went up to New York with Tom on the train one afternoon and when we stopped by the ashheaps he jumped to his feet and taking hold of my elbow literally forced me from the car.”
Tom and Nick have arrived at the garage in the bad section of town, and it is rapidly apparent that Tom is no stranger to this locale. Following some minor pleasantries, which quickly become strained, between Tom and Wilson, the garage owner and, it will soon be revealed, the husband of Tom’s mistress, the latter makes her entrance:
“She was in the middle thirties, and faintly stout, but she carried her surplus flesh sensuously as some women can. Her face, above a spotted dress of dark blue crepe-de-chine, contained no facet or gleam of beauty but there was an immediately perceptible vitality about her as if the nerves of her body were continually smouldering.”
To answer the question, then, Tom and Nick visit the garage so that former can introduce the latter to the woman with whom he is engaged in a disturbingly-public extramarital affair.