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. The Iremongers are a mean and cruel family, robust and hardworking, but Clod has an illness. He can hear the objects whispering. His birth object, a universal bath plug, says 'James Henry', Cousin Tummis' tap is squeaking 'Hilary Evelyn Ward-Jackson' and something in the attic is shouting 'Robert Burrington' and it sounds angry. A storm is brewing over Heap House. The Iremongers are growing restless and the whispers are getting louder. When Clod meets Lucy Pennant, a 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.