Heavy snowflakes dance in the twilight as Emily Laing finds London missing for the first time. But how can that be? A whole city doesn't just disappear like that, along with all its chimneys, residents, and secrets. Could it have something to do with the two strange old ladies who abduct Emily? Or is it connected to the orphan girl who suddenly appears on the steps of a subway escalator? Once again, Emily and her companions—the alchemist Wittgenstein, Maurice Micklewhite, and the clever rat Minna—must descend into the depths of the ancient metropolis. For here, in the magical city beneath the city, lies the answer. And the danger...