We are a little after halfway through the 4th series of Sherlock and the show has already delivered the greatest plethora of shocking events throughout the course of its run, The Lying Detective being far from an exception. The premiere had us all gaping to our screens and tearing up as we watched sweet Mary Watson (Amanda Abbington) get shot to death by a secretary slash terrorist. At this point, we thought that nothing was going to stun us more, the second episode proved us wrong with the unexpected reveal of the third Holmes sibling, Eurus. A sister, not a brother as many had expected. But let's take everything from the beginning.

The episode starts out strong, with Watson (Martin Freeman) going through his first session with his new therapist, where we also see that the grieving doctor has naturally not managed to let go of his deceased wife. Mary is standing next to him, talking to and consulting him, being her usual delightful self as if nothing has changed, yet everything has.

"This isn't real, I am dead" she insists, for his own sake and their daughter's, something which Watson simply refuses to acknowledge because yes, it hurts so much to do so. Freeman gives a spectacular performance throughout the episode, going through various emotional stages to deal with his loss, denial being the obvious and most prominent, as is, of course, anger. Anger towards his best friend who he wants to blame for Mary's death, yet knows that he can't because Mary's sacrifice was her own choice and not Sherlock's. But until he reaches the point of accepting that, he has to face that anger and let it out, which he does in that very intense scene in the morgue, where he beats Sherlock (Benedict Cumberbatch) till he bleeds and cannot defend himself anymore. And Sherlock lets him do it. "It's ok. I killed his wife", he says, because ultimately he feels the responsibility on his shoulders. Mary died to protect him when he had vowed to give his own life to protect her and her family. Yet, he failed.

While Sherlock repeatedly claims to be detached from every form of human emotion, this episode is proof that he is actually far more attached than he even understands. Sherlock has feelings that run deep, yet he fails to see them, as obvious as they may be to the eyes of a viewer. He has respect for Lestrade. He values Molly. He depends on Mrs Hudson and is protective of her. He may have even developed romantic feelings towards Irene Adler (Sara Pulver), with who he (surprise surprise!) keeps texting from time to time. And he loves the Watsons. John is his best friend, probably the only friend he has ever had. And Mary was a woman of incomparable strength, who managed to see through his crap and read him probably as well as he did with her. He let her in as she let him in and that was something Sherlock hardly ever came across in his life. Which is why he listened to her as she gave him her final case and went to hell. He filled himself with every drug he could think of, put his life on the line as she asked, and did all that with one single purpose: to save John. To save him from himself and his grief that would destroy him. To get him back to the game and back to his daughter.

In the series, this one was the most emotional scene to date, John reveals to both Sherlock and Mary that the man she believed him to be is not the man he truly is. He let her down. He almost cheated (thank God, he truly didn't, thank God). Yet that man, that person she held on such high standards, that's the man he wants to be. Freeman, Cumberbatch and Abbington managed to bring me to tears during those few minutes, one line making me more emotional than the other, the climax of the sadness being the comforting hug Sherlock offers his friend. A shoulder to cry on.

"I have this terrible feeling from time to time that we might all just be... human. Even you." One cannot even begin to explain the depth Sherlock's words delivered in this single line. He admits to not only being susceptible to humanity's weaknesses, but to thinking that the one person he always thought was beyond that was John. And it's ok even for him to be human. And he has to accept it and give himself a break. Truly astounding writing by Steven Moffat in this one, I wholeheartedly give him a round of applause.

The highlight of the episode though was the new member of the Fast and Furious team, none other than Mrs Hudson. We knew that she rocked already, but in The Lying Detective she took it to a whole new level of awesome, what with her exceeding speed limits while driving a wild sports car in order to get the handcuffed-to-her-boot Sherlock examined by John. Or with her pretending to be scared by Sherlock's yelling, only to trick him into letting her grab his gun and get him inside the car. Or with the way she threw everyone out of her apartment the moment John had to watch Mary's video message to Sherlock, and her fearless confrontation with Mycroft, calling him "reptile" and "stupid". You go Mrs Hudson! I'm always happy to see the side characters more involved into the plotlines, and this season has unfortunately let me down in that front so far, especially with the immense underused of Louise Brealey's Molly. But at least Mrs Hudson got some serious action in this one and for that I'm grateful.

And on to the episode's most frightening aspects, Toby Jones scared the hell out of me with his depiction of insane, serial killer Culverton Smith. From the way he talked, to the way he moved and obviously to his freaking laugh, Jones projected a darkness like no other villain that has crossed Sherlock's path has. Not even Moriarty. The brilliance of the show, aside from the obvious, also lies in the fact that while all villains are dangerous and definitely mentally disturbed, they are not copies of each other. Smith is not a new Magnussen or Moriarty. He is a whole new entity, and a freakishly appealing one to say the least. He spoke of murder in front of 20 children and the media, and made it seem only natural to do so, because, in the end, those with power can do and say whatever the hell they want. It makes you think of so many men with power and how they can get away with everything simply because of who they are. Once again, the Sherlock team did a great work with the casting of Jones and of course with his story, that ultimately served the episode's biggest event: the reveal of Eurus.

I am proud to say I was one of those that managed to see through the grey hair or the round spectacles and frail form from the beginning. If there is one thing I've learnt from Sherlock it's that there is nothing random in its writing. There was no way that cheerful and bashful girl on the bus in The Six Thatchers simply hit on John out of nowhere. The writers would not include such a scene in the final cut if it were just one of John's mis-steps. Instead, they wanted to throw in the first clue for those who would second guess her purpose. Now admittedly, I only recognized the girl from the bus in the forms of John's therapist and Faith Smith, but I definitely did not realize who she truly was. And when she finally revealed herself in the end, my jaw dropped to the floor and my eyes popped out of my head. Sian Brooks truly outdid herself with the newest Holmes, playing 4 different characters in only 2 episodes, managing to make each one their own person, while at the same time giving Eurus the brilliance and insanity that naturally goes into every Holmes sibling. Yet another exceptional casting choice that I truly approve, as I had the pleasure of enjoying Brooks last year next to Cumberbatch's side as the Ophelia to his Hamlet. I seriously cannot wait to see what this coming Sunday's big finale, The Final Problem, will do with her and how the series will conclude.

What did everyone think of The Lying Detective? Take a vote on our poll below and let us know your full opinion in the comments.