Paranoia by Joseph Finder is available for free (it was $2.99 last December when I purchased it).
Book Description
By the New York Times bestselling author of High Crimes, Paranoia is a Grisham-esque thriller set in a post-boom 21st century economy. With his personal life in decay, a late twenty-something gets caught in one stupid act that spirals out of control, threatening to ruin the lives of thousands.
Adam Cassidy is twenty-six and a low level employee at a high-tech corporation who hates his job. When he manipulates the system to do something nice for a friend, he finds himself charged with a crime. Corporate Security gives him a choice: prison -- or become a spy in the headquarters of their chief competitor, Trion Systems.
They train him and feed him inside information. Now at Trion, he's a star, skyrocketing to the top. He finds he has talents he never knew he possessed. He's rich, drives a Porsche, lives in a fabulous apartment, and works directly for the CEO. He's dating the girl of his dreams.
His life is perfect. All he has to do to keep it that way is betray everyone he cares about and everything he believes in. But when he tries to break off from his controllers, he finds himself in way over his head, where nothing is what it seems and no one can really be trusted. And then the real nightmare begins...