Luther is on a leave of absence from the police force, laying low in a rundown cottage on the edge of England. But a visit from his old colleagues at the Met brings a shocking piece of news that draws him back to London in search of the truth. Meanwhile, a gruesome serial killer has struck the city. But this murdering mastermind is more than a match for the police, outsmarting them at every step. It’s not long before Luther is back in the Bullpen, determined to steal a march on the killer before it’s too late.