DNA doesn't lie. But what if the truth is dangerous? 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 from a Brighton beach 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...