Quarantine - Greg Egan

In 2034, the stars went out. An unknown agency surrounded the solar system with an impenetrable barrier, concealing the universe from humanity's gaze.
In 2067, Nick Stavrianos is hired to investigate the disappearance of a mentally disabled woman, Laura Andrews, from the institution where she was being cared for. Aided by a skull full of neural modifications, he follows her trail to the Republic of New Hong Kong, where an organisation known as the Ensemble has uncovered Laura's extraordinary secret: an ability that could transform the world.