In The Outstretched Shadow, which was named by VOYA as Best Science Fiction, Fantasy, and Horror book for 2003, Mercedes Lackey and James Mallory introduced readers to a complex new fantasy world populated by humans, centaurs, elves, talking unicorns, and demons. The Golden City of the Bells, where only humans live, is ruled by the Mage Council, practitioners of High Magic---a powerful magic that is stable and reliable, though rigidly controlled and performed only by men. Outside the City's walls, humans and magical beings mix freely and call upon Wild Magic---a system sometimes erratic, always driven by desire and need, and performed by both men and women. Now, in To Light a Candle, the Demon Queen sends her forces against her human and elven enemies, sowing distraction and death. In the human City, the Queen's agents work to divide the Council and foment rebellion among the City's citizens.

In the countryside, they target the most vulnerable and valuable---the young Elf Prince and the Wild Mages who might be the Demons' most dangerous enemies. To his own surprise, young Kellen, once the disappointing son of the great Mage who leads the City's Mage Council, has become a powerful Knight-Mage. Valued for his bravery and his skills as both wizard and warrior, Kellen joins the Elves' war councils. Yet he cannot convince the City of his birth that it is in terrible danger. Kellen's sister Idalia, a Wild Mage with great healing ability, has pledged her heart to Jermayan, a proud Elven warrior. Someday Idalia will pay a tragic Price for a world-saving work of Wild Magic, but until then, she will claim any joy life can offer her. Jermayan, who has learned much while fighting at Kellen's side and loving the human Idalia, finds that everything changes when he Bonds with a dragon while rescuing the Elf Prince and becomes the first Elven Mage in a thousand years.

Furious at her enemies' success with the dragon, the Demon Queen attacks in force. Light struggles against Dark, like flickering candleflames buried deep in the shadow of Obsidian Mountain.