Less Than Zero, Bret Easton Ellis, Vintage, 1985.
It begins as an odd little book, then draws you in and becomes fascinating, and finally a bit disturbing. At first the style may be a little off-putting, but very quickly the reader is drawn in. Ellis has a great ear for dialogue, and for choosing detail, sparse but effective, to build a scene.
The book features many parties, but Ellis makes each seem different. The action is varied within the repeated framework of parties and dinners and clubs.
There is a fairly large group of main characters, but Ellis handles them well, and the reader is never lost thinking 'who is that again?'
The only problem is the author's unnecessary need to 'top himself' late in the book; the characters have shown so much hedonism throughout, that Ellis goes over the top in the final chapters to create a climax. He needn't have bothered, to have maintained the status quo of the earlier chapters would have suited the novel and the ending much better.