This odd, solipsistic novel follows the entire life of a Frenchwoman named Lili (as evidence of the novel's interiority, most characters are introduced only by their first names). Lili grows up, a pious and studious girl, on the outskirts of Paris, half in love with her mother, half despising her philandering father. She loses a brother and a would-be fiancé to World War I (though she later discovers that her brother did not die honorably in battle, but succumbed to their family's unhappiness by committing suicide).

Lili's postwar life is not much happier; the war has challenged her pure childhood faith in God's provident sovereignty, and she spends more than a decade writing a book about her newfound atheism. She also falls tempestuously in love with Pierre, whose neuroses are so perfectly matched to Lili's that the affair is destined to end badly--though not before they have a son. Lili rediscovers some of her early passion for God in her single-minded devotion to this son, who is disabled. She also finds love again, this time in the arms of a woman.

DeWitt's writing is detached and somewhat difficult to follow; her excessive use of dashes (or, conversely, punctuation-free sentences) thicken the wall of abstruseness she builds around Lili's impenetrable character. The sex scenes are so remote that they seem voyeuristic; the sex is described as passionate, but it lacks the sensuality that Lili is supposed to have in spades. The book's title is appropriate, for it is solely about Lili's own inner world, which readers will have difficulty entering.