Kelley Armstrong is best known for her urban fantasy books -- for adults, teens and even children (if you count her books with Melissa Marr). 
 But as far as I know, "Sea of Shadows" is the very first high fantasy Armstrong has written. And it's not a half-bad way to start her new Age of Legends series -- she creates a fantasy world filled with dark magic, monsters and blood, countered by a pair of tough young girls who are equally adept with knives and magic. The main flaw? At times I could have used a lot more elaboration. 
 Moria is the Keeper who protects the village from hostile spirits, while her twin sister Ashyn is the Seeker who finds the dead and buries them before they can become troublesome. Now that they are sixteen years old, they lead the villagers on a specific day when the veil between the living and the dead is thinnest. Also, they each have a supernatural animal. 
 But then the village is invaded and destroyed -- the children are kidnapped, the men are turned into monstrous shadow-stalkers, and the women are slain. Even worse, the sisters are unable to stop it. Teaming up with stoic warrior Gavril and the mysterious Ronan, Ashyn and Moria set out on separate quests to right what has gone wrong -- and discover an enemy raising a nightmarish shadow army. 
 From the very beginning, Armstrong sets "Sea of Shadows" in a world that feels incredibly dangerous. There is no pretty little village set apart from the danger of the outside world... oh no, no, the characters live next door to a forest of madness, disease and death. There's graphic gore, lots of blood, demon-things that turn you into a grotesque cannibal, more dead bodies than a World War I cemetery, and "death worms" that can spit acid at you. 
 And Armstrong adjusts her writing to better fit a high fantasy story -- it moves quickly despite the heavy details, and some of her prose is downright lovely ("... watched the spring sun burn away the lace of frost"). It's not very clear what's going on in the first half of the book, but eventually the author sketches out the real threat to the empire, as well as some unexpected twists. 
 It also has a distinctively Japanese flavor. Some parts of the setting are pretty generic medieval stuff, but Armstrong weaves in some cultural attitudes and ideas into it -- consider the kitsune tattoo on Gavril's arm, or the Edgewood's resemblance to Aokigahara. 
 Both of the sisters are thoroughly likable heroines -- Moria is strong, stubborn and fiery, while Ashyn is shy and awkward. Ironically, at the beginning Moria has to stay at home while Ashyn has to go charging out into the forest. And they each have a budding romance, one with a quiet mysterious warrior, and the other with a feisty mysterious criminal living in the woods. 
 The biggest problem is that sometimes I could have used a bit more elaboration on the world that Armstrong has built, such as the religion that they follow (can we hear more about the goddess?). Instead we leap headfirst into the plot with few explanations about, say, what the empire is. 
 While Kelley Armstrong could give us some more details about her world, "Sea of Shadows" is definitely a solid start to a new high fantasy series -- and the two buttkicking heroines don't hurt either.