In the beginning of the novel she is attacked in a park on her way home and these people come and save her. Later on she finds out her mom was kidnapped I think.
I specifically remember a part where she is assigned a trainer and they have to go back to the hideaway where there are flat screen TVs and motorcycles (because these kids can manifest anything with their mind) and the trainer has her falling down a dirt endless hole and she is trying to get out so hard that her fingernails rip.
I think they can also shield themselves, e.g. making the house that they live in invisible.