Probation officer Cate Austin has moved for a fresh start, along with her daughter Amelia, to live with her police detective boyfriend, Olivier Massard. But when she realises just how casually he is taking the disappearance of a young girl, Ellie, Cate decides to investigate matters for herself. She discovers Luxembourg has a dark heart. As Cate comes closer to discovering Ellie's whereabouts she uncovers a hidden world, placing herself in danger, not just from traffickers, but from a source much closer to home.