When eight-year-old Jasmine Guichard gets lost in the catacombs of Paris, she triggers a sequence of events that she could never have imagined. And many that she will never know about.
While she is trapped in the darkness, a contract killer arrives in the city to wreak revenge on a paedophile who made a mockery of the justice system. D.S. Robbie Allen and D.C. Benedict Blewett are dispatched from Liverpool to find the killer before he strikes again. But when D.C. Blewett spots their mark, his senior officer refuses to believe him.
Meanwhile, Harry and Tristan are determined to find Jasmine and are helped in their efforts by a young nun who is not at all what she seems. There's more going on behind the closed doors of the Daughters of Charity of Saint Isabelle of France than meets the eye - a lot more.
When D.C. Blewett hands the proof of a European counterfeit gang to the French police, he is elevated to celebrity status. When he then alerts the world's media to events at the Daughters of Charity of Saint Isabelle of France, even his disparaging senior officer starts to take note.