Reviewed by Phil Boothman.

“M” begins with a large man (played by Vinnie Jones, which was an…interesting casting choice, to say the least) watching football as he sets up a large tripod and a man with his arms and legs tied together struggles on the floor behind him. He silently picks the man up, attaches the man’s feet to a hook and hoists him upside down, then picks up a knife and slits his throat.

Meanwhile, Holmes and Watson are talking about the fact that their arrangement is coming to an end soon, and she is working on a final assessment for his father. However, before she gets much out of him, they are called to the crime scene by Gregson, where there is no body but a large pool of blood on the floor. Holmes swiftly deduces that he was hung from a tripod, and announces that he has dealt with murders like this before, committed by a serial killer back in England called ‘M’, a man who has killed almost 40 people with no recognisable pattern in the past decade, and has never been photographed.

Watson is a little disturbed by how excited Holmes appears to be over this, and he tells her it’s because he has a second chance at catching a murderer, however that clearly isn’t the whole story. He also tells Gregson that M has referenced him in multiple letters, and a security detail is provided: he then tells Watson that he needs to get used to working on his own again, and will provide her with email updates on the case.

After her therapist tells her that she should consider a change of career to become an investigator alongside Holmes, Watson heads to the morgue to meet Holmes, who is examining the recently-discovered body of Vickers, M’s victim from the opening of the episode. Watson correctly deduces the location his body was dumped in from oil residue in his hair, and tells Holmes that she’s going to miss working with him. This was a really nice scene, because it perfectly contrasts the personalities of the two leads: Watson essentially opens up to Holmes, and displays genuine affection, while all Holmes can do is look vacantly back at her without a single word.

They return to the brownstone to find a note from M, telling Holmes that he is a ‘mouse chasing a lion’: and Gregson decides to move them to a safehouse, but Holmes insists that they will be fine and M won’t attack them. Once everyone has left, however, he checks his personal security cameras and gets his first glimpse of M’s face: he then delivers it to several ‘associates’ around the city and tells them to contact him if and when they see him. One of them does spot M and turns up at the brownstone, revealing to Watson what happened: she confronts Holmes who says, rather chillingly, that he has no intention of finding M and turning him over to the police, but he has every intention of torturing and murdering him.

He goes on to explain that M is the one who murdered Irene Adler as a warning for Holmes, and it was her death which began his spiral of self-destruction: so he is planning revenge not only for Irene’s murder, but also the fact that his life was ruined as a result. Watson tells him that she has to tell Gregson, but she doesn’t stop Holmes from leaving with a bag full of weapons.

Having seen him receive a coded text message earlier, we now see M attempting to kidnap a young woman in her house: however, he is stopped by Holmes who knocks him out with a baton and takes him to a warehouse. What follows is one of the best sequences that has appeared in the show thus far: Holmes confronts M about Irene’s death, to which M responds that he had no part in that particular murder. Holmes repeatedly tells M (who turns out to be named Sebastian Moran, a character who appeared in the Arthur Conan Doyle story ‘The Adventure of the Empty House’) that he’s a terrible liar and Holmes knows he did it. Moran then tells Holmes that he is not, as suspected, a serial killer: rather, he is an assassin being paid by a mysterious figure to kill people and leave notes. He also admits that he didn’t even know that Holmes had moved to New York, and had not followed him as Holmes had suspected.

Moran quickly realises that he’s been sold out by his employer, and tells Holmes that he was in jail when Irene was killed, and it was a copycat attempting to manufacture resentment in Holmes. He also, in the best moment of the episode, gives Holmes the name of his employer: Moriarty.

He then attempts to reason with Holmes, stating that if he kills him, Holmes will have lost his best clue to finding Moriarty: Holmes, in turn, assures Moran that he’s not an average man, and sticks a knife into his stomach.

After Watson works out where Holmes had taken M, the police turn up only to find that Holmes had just turned Moran over to police custody, having stabbed him in one of the few locations of the human body that wouldn’t cause any lasting damage. He tells Watson that Moran didn’t kill Irene, and then tells her that he’s going to miss working with her. As he leaves, Watson puts in a call to Holmes’ father telling him she’s worried about Holmes and wants to stay on: even though she later receives an email stating that her services will no longer be required, she tells Holmes she’ll be staying with him after all.

The episode closes with one final tease, as Holmes removes all the evidence from the M case from his wall, replacing it with a card with a single word written on it: MORIARTY.

Verdict: 9/10

Aside from a slightly suspect turn from Vinnie Jones, “M” is, without a doubt, the best episode of Elementary thus far: it gave us a glimpse into the dark side of Holmes’ psyche and a hint of what he is really capable of, while also showing the softening of his attitude towards Watson in a few really great scenes. Plus, I’m a sucker for a teaser, and the introduction of Moriarty as a concept is a good one!