Out of Mind (S03E01)

DI Chappel unexpectedly encounters his former superior, DS Frank Vickers, while at a Soho brothel, where hidden pasts resurface, putting both the vice squad and Chappel's private life at risk. As he delves into the murder of a sex worker, Chappel seeks out an old flame for assistance, only to find that she has turned her back on the sex industry and moved forward with her life.