When Charlie discovers an intruder in her kitchen she has no warning of the adventures which are to follow. The strange creature is Skrubb, a Gremal who has been sent to The Surface by his tribe who dwell deep in the Underworld. His cousin Skreng has stolen a sacred scroll and Skrubb has just three days to recover it - or his family will be put to death. Charlie recruits her bookish friend Ollie to help in a desperate race against time that takes them from the darkened halls of the British Museum to the modern towers of Canary Wharf, from caverns deep below the Tower of London to the corridors of power at Westminster. The quest will not be easy, for Skreng does not want to be found and others are also on the trail.