D.M. Cain 
The Phoenix Project [EPUB ebook] 

In a world that has descended into chaos, Raven Kennedy becomes a part of the Phoenix Project. Across the country, prison inmates fight to the death while the nation cheers them on. 
While struggling with his past, Raven faces the prison’s most ruthless killing machines. With the real war raging inside him, Raven fights for redemption.
But can he survive long enough to unravel the anger and regret that shackle him – and find the forgiveness he seeks?