Jo Conran is a single mum working as a flight attendant. Her son is serving a fifteen-year sentence in a Bulgarian prison for a murder he swears he did not commit. Jo is approached by a gang who know all about her son and is blackmailed into using her job to smuggle drugs. She soon finds herself pulled into a murky underworld of corrupt cops and hired killers, forced to carry out their orders with no escape in sight. However, no matter how far Jo finds herself from her old life, her mission remains the same, to keep her son alive.