Book Review: Shadow Over Avalon

I don't normally write book reviews, but I'm writing this one at the request of my crit partner from OWW and current beta reader, C.N. Lesley. (I'm using her pseudonym.) One of the books I critiqued for her on OWW is Shadow Over Avalon. Here's the book description from Amazon:

Fortune twists in the strongest hands. This is no repeat; this is what happens next.
A man, once a legend who bound his soul to his sword as he lay dying, is now all but a boy nearing the end of his acolyte training. Stifled by life in the undersea city of Avalon, Arthur wants to fight side by side with the air-breathing Terrans, not spend his life as servant to the incorporeal sentient known as the Archive. Despite the restrictions put on him by Sanctuary, he is determined to help the surface-dwellers defeat predators whose sole purpose is to ensure their own survival, no matter the cost.
Ashira, War Maid and princess of the surface-world, is ready to sacrifice her life to defend her kin, but when she is betrayed and cast out of the life chosen for her, she must choose whether to die with honor or become one of the creatures her kinsmen fear and loathe.
Following two threads of time, C.N. Lesley’s new incarnation of the Arthurian tales of old delivers the perfect blend of science fiction and fantasy. 

 At the beginning of this story, Arthur is a youth with great psionic abilities who is being pressured to sire a child whom he fears will be exploited. He wants to go to the surface, so he studies the life of Shadow, a Terran warrior whose own mental abilities are on a par with his own. The Archive, the computer that runs Avalon, can provide sensory feedback of Shadow's life that is so complete it's addicting. As Shadow's story advances, Arthur struggles for the freedom to make his own choices in his world, but he doesn't fully understand how his story and Shadow's intertwine until the end. The transitions between Arthur's scenes and Shadow's are well-marked, and there's no confusion between them, even when the same characters appear in both worlds. Each separate world (the underwater city and the surface world) is well-developed. I empathized the most with Shadow, who starts the story as the War Maid Ashira but loses so much over the course of the story she needs a new name. Arthur took longer to grow on me, but he matures over time. This story is an amazing twist on the legend of King Arthur, and I look forward to reading the sequel, Sword of Shadows.