Perilous - Rise of the Charioteer Series, #3

A desperate kingAn apprentice healerAnd the race to beat the deadly nexus. Life has barely returned to normal when the Oracle brings another dire quest to Chaddesden. This time, though, it's not a knight she seeks, but a healer. Brynwen will need all her skills to find a priceless stone her enemy needs to reshape the world.  Brynwen faces a dilemma when the King of the Underworld seeks her help; she must choose between aiding his people in overcoming a fatal illness or continuing her mission. However, danger for the unwary lurks in the depths.
Can Brynwen navigate the king's subterranean realm in time, or will she remain trapped in the underworld forever?   For fans of Percy Jackson and Chronicles of Narnia, this tale of medieval historical fantasy is a must!