Don't get too excited, this isn't a new series of Sherlock but it is another chance to see the most recent endeavours of the sleuth and his sidekick as season four arrives on RTE. It sees the detective (Benedict Cumberbatch) investigating the apparent return from the dead of his old enemy Moriarty (Andrew Scott), but another strange case is soon demanding his attention. Scotland Yard is baffled by a mysterious criminal who is defacing images of Margaret Thatcher, and Sherlock is convinced there is a more sinister purpose at work behind these acts of vandalism - which may have a connection to Mary Watson's dark past as an assassin.