As Will Burrows continues to search for his lost archaeologist father in the strange underground world he has discovered, he stumbles across a sinister plot with terrible implications for the world above.

Styx and their cohorts of deadly Armagi have swept across England, leaving death and devastation in their wake. Only a miracle can save the day and, in the inner world at the centre of the earth, Will and Elliott might just have stumbled upon one as they uncover ancient secrets that are fundamental to all human and Styx life. "Will y Elliott huyen de nuevo hasta las entrañas de la tierra. Con el apoyo de un pequeño equipo que sobrevivió a la plaga...