DC Anna Travis (Kelly Reilly) is back, reunited with the inimitable DCI James Langton (Ciarán Hinds), to face her most challenging and terrifying case yet. When the body of a young woman is discovered, sadistically mutilated and drained of blood, it would seem an ominous re-enactment of the infamously unsolved murder from 1940s Los Angeles, dubbed the 'Black Dahlia'. Travis races to stay one step ahead of the killer, using the original case as some sort of instruction manual. Meanwhile, the underlying sexual friction between her and Langton threatens to derail the investigation. However, they must pull together to stop this depraved copycat killer before he strikes again.