Nora chose the fifth floor of an old Parisian building for one reason only: she wanted to be certain there'd be no one above her. But a few nights after moving in, a sixth button appears in the lift, between the five and the alarm. A button that shouldn't exist, in a building with only five floors.

When she finally dares to press it, Nora discovers an impossibly long corridor, a flat that rebuilds her own life with unsettling precision, and a woman who knows her better than she knows herself: Jeanne, her great-great-grandmother, who vanished in 1952 and whom the whole family had long given up for lost. Jeanne offers her something no one else could: everything Nora has lost, restored to her forever, on a single condition — never go back down.

As Nora pulls at the thread, she discovers she isn't the first woman in her family the sixth floor has tested, and that the choice she's about to make was already made once before, in another era, with consequences that still reach her today.

The Sixth-Floor Flat is the second novel in Michel Hayoit's family suspense collection, following The House That Remembered — an intimate domestic mystery about the secrets families inherit in silence, written for readers who love houses with memory, lines of women bound by what was never said, and endings that comfort more than they frighten.