From "About a month after ..." to end.
____Albertine, preparing to visit her aunt, Mme. Bontemps, for a few days, arranges to spend the night at the hotel because it's close to the train station. And she tells the narrator he "can come up and sit by my bedside while I'm having my dinner." As you can imagine, he's thrilled: "Her words carried me back further than the time when I had been in love with Gilberte, to the days when love had seemed to be a thing that was not only external to myself, but achievable." So he goes to the room in an exhilarated state, finding her in bed and wearing her nightgown. He's "intoxicated" by "her naked throat and her excessively pink cheeks," and the moonlight, the sea, and "the swelling breasts of the closest of the Mainville cliffs":
I leaned over to kiss Albertine. Had death chosen that instant to strike me down, it would have been a matter of indifference to me, or, rather, it would have seemed impossible, for life did not reside somewhere outside me: all of life was contained within me.Bad move.
Recovering from her startled and angry rejection, which ends with her pulling the bell to call for a servant, he gives her up. When she returns from her visit to her aunt and forgives him, warning him not to try anything like that again, he turns his attentions to Andrée.
He reflects on Albertine's popularity and the advantages that her beauty has given her, which overcome her status as the dowryless ward of the stingy M. Bontemps. She tells no one else about "our bedside scene, which a plainer girl might have wanted to share with the world." And he "even began to wonder whether her violent reaction might not have been prompted by some other reason, such as squeamishness (if she had suddenly noticed a bad smell about her person, and thought it might offend me), or timidity (if she believed, in her ignorance of the realities of lovemaking, that my state of nervous debility might somehow be contagious, contractable from a kiss)."
For her part, she wonders, "What sort of girls must you be familiar with to be surprised at what I did?" (He has already reflected that her behavior was different from what he expected after "Bloch first informed me that women were there for the having.") And she concludes with "I'm sure you're just teasing me! Andrée's the one you really like -- admit it! And I'm sure you're right -- she's much nicer than me, and she's beautiful! Oh, you men!"
But he has already realized that he doesn't love Andrée: "she was too intellectual, too high-strung, too prone to ailment, too much like myself." She was "never happier than when translating into French a novel by George Eliot." His obsession with Albertine only increases:
It may be because the personalities I perceived in her at that time were so various that I later took to turning into a different person, depending on which Albertine was in my mind: I became a jealous man, an indifferent man, a voluptuary, a melancholic, a madman, these characters coming over me not just in response to the random recurrence of memories, but also under the variable influence of some intervening belief which afected this or that memory by making me see it differently.It's clear that instead of him possessing her, she has possessed him.
And so the summer ends: "the concerts came to an end, the weather turned bad, and my girls left Balbec, not all at once, as the swallows leave, but within the same week." He and his grandmother and Françoise linger at the hotel, where only a few guests remain, including some wealthy and aristocratic young men, one of whom is the Marquis de Vaudémont. They invite him to join them at a restaurant, but he declines. (But since the name has been introduced, we can bet we'll encounter the marquis again.) The hotel grows emptier and colder, but it has become to feel like home for him, and he is "all the more determined to come back one day."
Finally he and his grandmother and Françoise leave, and we set out on The Guermantes Way.