Who is Dr. Cable from Pretties and what is their importance?

Dr. Cable is one of the leaders in Special Circumstances. It was Cable, who initially contacted Tally and convinced her to go to the Smoke in order to allow Special Circumstances to find it and end it. In this novel, Dr. Cable comes to Tally and asks her if she would consider becoming a Special Circumstances. Tally turns her down. However, after Tally is caught in the New Smoke camp, Dr. Cable has her forcibly turned into a Special Circumstances agent.