I must note that my reaction to this book might have been different if I hadn't read Blue Cats and Chartreuse Kittens first for reasons that will be obvious if you read this review:
You may regard it -- and the rest of this review as just a bit spoilery because the heroine doesn't learn something for a few chapters.
Namely, that she's a synesthete. I realized that from the descriptions as she wakes up in the mental institution, unclear about the last few weeks and still remembering how she had confronted another girl, Tori, in her school and made her disintegrate.
She was incoherent and flipping out after that, and so this is where she ended up, though she is transferred to a new one in the opening chapter. And the police urge her to tell them if she remembers anything, anything at all, that would help them find Tori, who disappeared that day.
She meets people, tries to appeal her involuntary commitment and fails, meets a scientist who identifies her synesthesia, and makes more discoveries. And the book winds on, taking in how she knew that Tori was adopted, a boy at the place who does a lot on the computer, a fire, not taking drugs and having it backfire, a discovery about lying, and much more. It's a marvelous work.