Fridolin and Albertine are a couple belonging to the solid, respectable bourgeoisie.
Their union is founded on "a perfect interpenetration of feelings and ideas."
Yet, a masked ball is all it takes—where both had been courted, he "with insinuating kindness," she

at first fascinated and then suddenly offended...
with an insolent swearword

, for them to be brushed by,

and not for the first time, a shadow of adventure, of freedom and of danger

.
From this insignificant prelude arise the hint, the desire, the possibility of a second life, made of transgressions, voluptuous secrets, daring acts, and even cruelty.
Fridolin, a physician by profession, must visit a patient in the evening.
During the night, seized by a restlessness unpredictable in so measured a man, he is gratified by a daughter’s declaration of love at her father’s bedside, is on the verge of brawling like a schoolboy with a gang of drunken students, finds himself in a disreputable neighborhood and accepts the invitations of a young prostitute, and finally attends an extraordinary gathering.
Men, dressed in "festive costumes as white, blue, and red cavaliers," dance with women,

their head, forehead, and neck draped in dark veils, small black lace masks over their faces, but otherwise entirely naked

.
At first the scene is austere.
Then the men rush

all toward the women, who received them with furious, almost wicked laughter

The ineffable pleasure of the sight transformed within him into an almost unbearable torment of desire

, but Fridolin is soon discovered.
He is an intruder; he would be punished were it not for a lady stepping forward, naked but veiled, who declares she will "redeem" him, assuming the consequences of her act.
He is safe and returns home.
Albertine is fast asleep, but, upon his arrival, awakens with a shrill, sinister laugh.
It is the conclusion of a dream in which Albertine imagines being amid "an infinite sea of nakedness" and witnessing the torture of Fridolin, "without feeling pity or horror, with absolute detachment": right up to the murder of her husband, during which

I was tempted (said Albertine) to mock you.
to laugh in your face

, to wish "that you could at least hear my laughter while they crucified you."
Fridolin is shaken and, after entertaining the fleeting notion of "beginning a new life under another guise," resolves to take revenge on his wife by somehow seeing the night's adventures through to the end.
But retracing his steps proves disappointing and concludes at the morgue with the sight of the lady's corpse—the one who saved him, and who was likely poisoned as punishment.

A stranger, an unknown woman never met before...
represented nothing to him, nor could represent anything other than the pale corpse of the previous night, irrevocably destined for decomposition

"No dream is entirely a dream," just as,

the reality of a night, and indeed not even that of an entire human life, does not signify, at the same time, its deepest truth

.
A part of ourselves is, therefore, dark, pierced only with difficulty in reality, yet more readily knowable through fantasy, in dreams.
This concept, the central thread of the novel, can bear two meanings.
The first is comforting, albeit limiting, and reflects what Lorenzo the Magnificent states so well in a sonnet:

O Love, too envious of my bliss, let me at least be happy in sleep

.
The second meaning is more unsettling and leads back to the fact that each of us assumes that

the dwelling place of one's own mind is not, cannot be, entirely opaque to him

(Teju Cole, Open City).
We do not rationally accept what we truly are because we would have to acknowledge that we are not heroes.
It is no coincidence that in the novel Fridolin does not go all the way, even though he would like to: he does not have sexual intercourse, for example, with the young prostitute, just as he would like, as a nobleman, to refuse the lady's sacrifice.
Albertine, on the other hand, whose second life unfolds only in dreams, is free to give unbridled rein to her lasciviousness and her longing for transgression (she, married young and still a virgin), and to display coarsely the contempt and rancor toward her husband, rationally repressed.

The novel's flaw lies in the sluggishness of the plot, which could be encompassed in a few pages, but which the writer instead drags on with pedantry.
In fewer than a hundred pages, he manages to make the story tedious and prolix.

Why not read it? It is pointless.

Dream Story