A Flame in the North — Lilith Saintcrow

From New York Times bestselling author Lilith Saintcrow comes a thrilling Norse-inspired epic fantasy about ancient myth and magical destiny.
 
The Black Land is a myth: Centuries have passed since that Great Enemy was slain. Yet old fears linger, and on the longest night of the year, people in the South still light ritual bonfires to banish the dark.
 
In her village, this duty falls to Solveig, a girl favored by the gods with powerful fire magic. But when her brother kills a Northern lord's son during the ritual, it is Sol who faces punishment, by being weregild -- part hostage, part guest -- in the North for a year and a day.
 
As she journeys to her captivity, Sol starts to realize that the Black Land is no myth. The forests teem with foul beasts. Her travel companions are not what they seem, and their plans for her magic are shrouded in secrecy.
 
With only her loyal shieldmaiden and her own wits to rely upon, Sol must learn to master her powers and wrest control of her fate. For the Black Land's army stirs, ready to cover the world in darkness -- unless Sol can find the courage to stop it.