DNA expert Dr Sian Love has settled into running her own investigative agency and living with her partner, Kris. She's also started seeing a therapist to work through her traumatic past - a big step for Sian. Her life threatens to descend into chaos again when a teenage girl shows up at her office claiming to be Courtney Johnson - a child who went missing in Nottingham over fifteen years ago - but refusing to let Sian test her DNA. Wary but intrigued, Sian reluctantly revives the undercover skills she learned during her days as a police officer and begins investigating. But revisiting the past has consequences...