Sherlock waits to see where Moriarty will make his posthumous move. One mysterious case in particular baffles Scotland Yard - but Sherlock is more interested in a seemingly-trivial detail. Why is someone destroying images of the late Prime Minister Margaret Thatcher?

Cast: Benedict Cumberbatch, Martin Freeman, Amanda Abbington, Louise Brealey, Sian Brooke, Lindsay Duncan, Mark Gatiss, Rupert Graves, Una Stubbs