Clod is an Iremonger. He lives in the Heaps, a vast sea of lost and discarded items collected from all over London. At the centre is Heap House, a puzzle of houses, castles, homes and mysteries reclaimed from the city and built into a living maze of staircases and scurrying rats. And Clod has a peculiar illness. He can hear the objects whispering.
A storm begins brewing over Heap House. The Iremongers are growing restless and the whispers are getting louder. When Clod meets Lucy Pennant, a servant girl newly arrived from the city, everything changes. The secrets that bind Heap House together begin to unravel to reveal a dark truth that threatens to destroy Clod's world.
