New series. When a series of monstrous and seemingly indiscriminate killings become ever more audacious and public, DCI John Luther and new recruit DS Catherine Halliday are confounded by a complex tangle of leads and misdirection that seems designed to protect an untouchable corruption. But, even as the case brings him closer than ever to the true face of evil, a reluctant Luther is forced to confront the unburied demons of his own recent past. Idris Elba stars, with Wunmi Mosaku and Patrick Malahide. Continues tomorrow.