Forever living vicariously through her confident, fearless friend Maddie, Isabelle decides to be a little brave one night and accompany Maddie and her new boyfriend to a club - but it's not just any club. Part of the infamous Devil's Backbone motorcycle club, Maddie's new boyfriend introduces her to a new world, a perturbing world that has existed unbeknownst to Isabelle in her little hometown in Colorado for years, underground and dangerous. And he also introduces her to Hunter, one of the club's most prominent figures - and with it, everything in Isabelle's pristine, mundane unravels for better and for worse.