Wow. This book was so cool. (I think I repeated that to myself about every chapter or so as I read.) It will be difficult to review without giving too much away, but suffice to say it is a fascinating, many layered story. It sucked me on every level, with each stage fascinating enough in and of itself I never expected another layer to be revealed--but each time the surface was pulled back, I fell deeper into the story. It is the kind of novel in which you feel completely immersed, from beginning to end.The synopsis:Once upon a time there was a girl who was special.This is not her story.Unless you count the part where I killed her.Sixteen-year-old Alison has been sectioned in a mental institute for teens, having murdered the most perfect and popular girl at school. But the case is a mystery: no body has been found, and Alison's condition is proving difficult to diagnose. Alison herself can't explain what happened: one minute she was fighting with Tori -- the next she disintegrated. Into nothing. But that's impossible. Right?Alison has special abilities that have been both blessing and curse for her entire life. She's a synesthetic, which means her senses are cross-wired; she can see and taste and feel sounds, letter and numbers have colors, colors have flavors, etc. They were endlessly fascinated for me as a reader to experience through Alison's narration, and I'd have been happy enough if they were the sole focus of the novel. Alison's time in the mental institution, her self-discovery and eventual acceptance and embracing of her differences would have made a fantastic story in and of itself.But Anderson took it a step further, gave it a paranormal / sci-fi twist that was at once surprising and expected; the set up was subtle enough not to be obvious, but kept the transition from feeling jarring and out of place. It was a transgressional twist, one that changed the whole tone of the novel and made me perceive everything that had happened before differently.There were two things that kept me from giving this five stars was the pacing. First, the twist happened in the last 20% of the novel, and while it never felt rushed as I was reading it, I'd have liked there to have been more explanation and description. Second, the resolution and explanation for Tori's behavior fell flat for me. It was all so coincidental and never rang true to me. As others have said, Ultraviolet gave me the same feelings that A Wrinkle in Time series did as a child. It is a fascinating story, and while the ending tied things up enough for it to feel complete, I do hope there are other books to come.