Herding Cats by Sarah Anderson

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?

When Alison meets Dr Faraday, a visiting psychologist, she feels an instant connection. More, he believes her story. But there’s more to Faraday than Alison can possibly imagine … and the answers he will give her are … extraordinary …