The Warrior's Daughter, by Holly Bennett
In The Warrior's Daughter, Holly Bennett takes Irish mythology, and creates a strong young female character who has to deal with the happenings and characters of the myths. Luaine tells her own story.
Luaine is the daughter of Ireland's greatest warrior, Cuchulain. She and her mother, Emer, begin the tale in awaiting his return from war. Luaine may be something of a disappointment to her father because she is a girl, and not a potential next generation of warrior. But she has some powers of her own, and this is recognized early by the King's most important Druid.
When Luaine's father is killed in battle, and her mother commits suicide in order to rest in his grave with him, Luaine is forced into adulthood and into the notice of the king before she is ready.
She is a wonderful heroine for this fantasy tale - well fleshed out, and with great strength and spunk, but also having enough innocence and vulnerability that she is interesting and believable.
I think a strength of the book is in the setting. The creation of a believable mythic world, with a real Celtic feel. The descriptions are evocative and magical. I really liked the book. And I recommend it for probably 14 and up.