Sherlock has dealt with some turbulence in recent years on its upward surge to international juggernaut. Series three had the problem of trying to top the sterling series two, bring back Sherlock from beyond the grave, breathe life into the usually bland Mary Watson and fill the Moriarty-shaped hole in the show. The product ended up feeling lukewarm with more misses than hits such as the rather uneventful and tonally bizarre wedding episode which felt like a waste of 90 minutes. However, undoubtedly the weakest episode of Sherlock was the succeeding Christmas special The Abominable Bride which sold itself as a break from the 21st century, which made the show unique, and set it in its original 19th century. The episode felt very self-indulgent on behalf of the writers with little in-jokes every minute and a plain confusing reveal when we learn the Victorian setting was Sherlock’s mind palace all along, a plot twist that would make M. Night Shyamalan cringe.

Bearing this in mind, series four felt like a partial return to form with moments of brilliance perhaps most noticeably the casting of Toby Jones as Culverton Smith, one of the creepiest villains to be seen on TV for a long time. Jones proves how he is one of Britain’s most underrated character actors as he inhabits this despicable man who is eerily similar to another Northern celebrity who abused his position of power, was celebrated and who was thought of as, like Culverton Smith, untouchable. This was an extremely brave choice from Moffat and Gattiss to tackle such a sensitive topic but this episode feels like a definite high point of the series which they do not seem to reach again.

Much of the negative criticism towards this new series, from critics anyway, is the focus on the big action set pieces and presenting Sherlock almost as a Hollywood action star. However, while the critics exaggerate anyway, in the original Sherlock Holmes books, Sherlock is known to be a keen boxer and implied to have wrestled with his arch nemesis Moriarty at the top of the Reichenbach Falls. So is it really a step too far to show Benedict Cumberbatch and Martin Freeman fighting the occasional baddie rather than spending the entire episode in 221B Baker Street and the crime scene like the older incarnations in the novels tended to do? Having said that, the explosion during the final episode that sees John and Sherlock jumping out of the windows of 221B and then in the following scene emerge without a single scratch is ridiculous.

Series four is mostly concerned with tying up many of the various threads from the previous three series with the first episode finally tying up the farfetched story arc of Mary: the international assassin. While the action of the series was wrongly criticised, as to some extent we need high stakes to engage a 21st century audience, the whole Mary storyline always seemed like the most unbelievable, and frankly boring, part of the show which is a difficult task when other stories include an over the top villain who steals every scene he is in and an elaborate plot to blow up the Houses of Parliament. As Moriarty’s thread is also tied up with a brief five minute cameo in the final episode where he dances to Queen, implies he has slept with one of his male bouncers and imitates a train in a high pitched voice, one cannot help but feel that it was a waste of such a formidable and iconic character.

Including Moriarty in the final episode detracts from the ultimate villain of series four, Sherlock’s sister: Eurus Holmes. I was one of many that was none the wiser when we are introduced to the flirtatious Scottish redhead, the European therapist and the fake Northern daughter of Culverton Smith, and are then informed they are all the same person. Sian Brooke proves to be a talented actress whose use of accents and ability to inhabit different characters is extraordinary but ultimately feels wasted as she sets up some fairly random traps, all designed to make Sherlock feel empathy towards others. While the whole ‘secret sister’ twist feels cliqued, the performances of all the ensemble make us buy into it. Benedict Cumberbatch is given a chance to shine with his withdrawal storyline, Martin Freeman shows a more vulnerable side as he deals with the loss of Mary; and the likes of Mark Gattiss’s Mycroft and Una Stubbs’s Mrs Hudson are given some well-deserved screen time compared to previous series.

While the series boasts some genius moments, good as always performances and a satisfying tying up of all the loose ends, it ultimately does not leave us begging for another series.