The Stone Demon - Tapa blanda

When the newly-released demons set the Order of the Crow an impossible ultimatum ― deliver the Philosopher’s Stone, or suffer fatal consequences ― alchemist’s apprentice Donna Underwood must recreate the mythical artefact before the world is plunged into a modern Dark Age. But will she succeed when she finds herself pitted against a vengeful demon king, not one but two Faerie queens, an immortal Magus with his own shadowy agenda, and her own dangerously unpredictable powers?

Donna must be willing to make the ultimate sacrifice, but even death may not be enough...

The just-unleashed demon hordes have delivered an impossible ultimatum to the Order of the Crow: produce the Philosopher's Stone, or suffer a deadly reaper storm of retribution. If Donna cannot recreate the mythical artefact, the world will be plunged into a devastating modern-day Dark Age.
Pitting her dangerously unpredictable powers against a vengeful demon king, two maleficent faery queens and an immortal magus with his own shadowy agenda, Donna must be willing to make the ultimate sacrifice. But, this time, death may not be enough...
The final, breathtaking story in the Iron Witch trilogy.