Friday Friday, ABC, 8.30pm The Lond on Underground tube network isi the seedy backdrop for this two-p par t investigation. A hive of activity an nd thousands of harried people, it se eems at once the best and worst place to o commit a crime. Sitting on a busy train surr rounded by people lost in their own though hts (and phones), it is often a ver y lonely place e, despite the hustle and bustle. Tonight, ini “Falling Angels (Par t 1)”, Nikki (Emilia Fox x) and Jack (David Caves) investigate a ma an run down and killed by a train. When a fe male vicar is then murdered after being follow wed on the underground, the team tr y to build d a case against her husband.