The final battle between demons and the band of humans (plus witch and monster) who call themselves the Guardians approaches like a storm over the dark horizon. The demons are marshaling the vast resources under their command to dominate the two worlds, Sky Land and Hidden Land. They lack only a powerful talisman, a semi-mythical red crystal known as the Heart of Arundel. To obtain it they will undertake any desperate measure, and the murder of the Guardians' leader and his witch companion is a primary objective. the fate of humanity hangs in the balance as the race to find the Heart comes to its stunning conclusion in this, the fourth and last novel of Quartet for Witch and Demons.