Lost Weekend

S1, E3: Set in London's moneyed Belgravia, where wayward aristocrat Dominic Cotterall is besieged by accusations that he's murdered his girlfriend, Arla Beckman, who's been missing for several days. Dominic is determined to disprove the slurs against him, but colleague Bryony Phelps is convinced he killed her, and won't rest until she's got to the truth