Valley of Bones - Diane E Samson - Bog

A strong female comes of age in a dark time.
Princess Anna is left to rule Sunderland when her father, brother and presumed fiancé Jack ride to battle the devouring creatures in Jack's home kingdom of Oclen. She must establish herself as a strong leader with the Sunderland council and a neighboring king who brings along two handsome princes to negotiate an alliance.

Trouble erupts when pillaging marauders attack outlying Sunderland villages, causing the council to lose confidence in Anna's leadership. As Anna waits in trepidation for word from her father's army, all she hears is silence. Her scouts never return. When the reports of a coming horror reach Anna, she forges an unlikely alliance and reverses her father's long-standing policies against gems of power. She trains Sunderland's remaining soldiers to fight with gems. She'll lead them to battle in a brave attempt to rescue her family, the army, and the one she loves.
But first she must survive the treachery brewing in her own court.
Find adventure and swashbuckling romance in book two of the thrilling young adult epic fantasy series, Gems of Fire!