Fascinated and horrified by the rise in "homegrown" radicals, ambitious journalist Sam goes undercover in an extremist jihadist cell in Paris, determined to uncover the roots of the phenomenon. Following his initiation into the group, however, events accelerate at an alarming rate, and soon Sam is in way over his head. Turning to the police for help, Sam is instead recruited as an undercover agent by a pair of unscrupulous cops, who proceed to blackmail him into embedding deeper into the cell in order to feed them information. Events quickly spiral out of control, and Sam risks his life as the wildly unpredictable leader of the cell plans an attack in the heart of Paris.