Code Zero - Marc Elsberg

ZERO, an anonymous activist, has given the world a warning: stop the tech giants before it’s too late. But is anyone listening? Thousands of teenagers are signing up to Freemee, the biggest new social media site, uploading personal information in exchange for advice on what to eat, how to dress, even how to choose their friends. No-one questions what Freemee is doing with all that data. Until hundreds of users begin to take their lives. What will it take to bring down the Freemee mastermind, and who is up to the job?