In the kingdom of Valdris, the dead do not rest. They sing.

Beneath the Obsidian Throne, in a crypt carved from black stone and older bone, the bone choir has kept its vigil for a thousand years — the memory of every soul the kingdom has ever lost, folded into one endless song. Mirelle Voss, a bone-warden's apprentice, was born with the gift to hear them. She was born to keep them.

But the song is changing. A wrong note has crept into the harmony, and the dead are waking. When the blood tax takes her friend Tomas, Mirelle hears the choir sing his name — and she understands that the throne is not a seat of power. It is a mouth. And the thing that has been feeding on the kingdom's memory for a thousand years is almost ready to be born.

To stop it, Mirelle must descend into the Mirror Hall, where the obsidian mirrors show her worst self. She must face the First King's bargain, the original pact that created Valdris. And she must decide what she is willing to forget — because the price of silence is everything she has ever loved.

The dead are singing. The choir is hungry. And the last of the First King's line is the only one who can close the door.