Reviewed by Phil Boothman.

As if by a sprinkling of Christmas magic, Elementary answered my hopes and delivered an episode far superior to the one that preceded it. Not only was the main plot far more engaging, but I actually cared about the subplot, and the whole episode was a lot more enjoyable that “You Do It To Yourself”.

Part of what made “The Leviathan” a much better episode was that the mystery to be solved, while eventually becoming a murder case, began as something very different, and generally quite refreshing. The episode opens with a group of masked people robbing a high-tech bank vault, which turns out to be the titular ‘Leviathan’. Naturally, Holmes gets an early-morning visit from the head of Casterly Rock Security (an entirely random reference to the location of the same name in Game of Thrones), the company that designed the vault, and a request for an investigation and the information that the Leviathan was broken into once before in the past.

Arrogantly, Holmes tells him that the job will only take an hour, and yet when he gets to the vault he is completely stumped by one part of the security system: the number code which changes randomly every two minutes. After spending fifteen straight hours attempting to work it out, Watson observes that this behaviour is typical of something called a ‘dry drunk’, applying the same level of obsession that he would otherwise apply to drugs to the security system, and he gets in a Holmes-rage and busts the keypad apart with an axe.

Holmes decides to track down and question some of the members of the original crew who broke into the Leviathan, with the reasoning that one of them probably sold the secret on to the second crew: the only member of the original crew who agrees to talk tells Holmes that the mastermind of the plan, now deceased, sold the secret to a legendary criminal called ‘Le Chevalier’. No one has ever tracked him down, but Holmes finds him within the space of a few hours: he and Watson go to his house, find an original Picasso hidden behind a cheap replication. However, Le Chevalier’s son informs them that he couldn’t have robbed the vault two days ago, as he had a debilitating stroke two years earlier. They hand all the stolen goods in to Gregson, with the exception of the Picasso, which Holmes subsequently hangs up in the brownstone, supposedly on a temporary basis.

Faced with a series of dead ends, Holmes soon works out from the transcripts of the court case that four members of the jury had skills comparable to those of the original crew, and sets about tracking them down. However, the first one that they visit turns up recently dead, pushed out of his apartment window by someone who took his share of the diamonds and left a small blood sample on the floor.

Holmes convinces Gregson to get the members of the jury into the police station to get DNA samples from all of them, with the exception of one of the four robbers who also turned up dead. One jury member, incidentally one of the four Holmes believes were involved, a juror named Jeremy Lopez, is hesitant to give a saliva swab. After some mild coercion, he reluctantly gives it up, and it turns out not to be a match for the blood they found on the apartment floor: that blood turns out to be a match for a young woman whose house they search. However, from the evidence they find there, they find her guilty of something else: being a borderline perfect human being. Holmes expresses his frustration that he can’t fit her into the crime, when Watson reveals that the woman was heavily involved with caring for leukemia patients, to the point that she was a bone marrow donor.

They bring Lopez back in, and Holmes reveals his ace in the hole: Lopez has leukemia, and received a bone marrow transplant from the young woman whose blood showed up. Apparently, receiving a bone marrow transplant means that the recipient’s body begins replicating the donor’s DNA, thus making it possible for the donor’s blood to show up in an apartment when it came from the recipient’s body. They show Lopez a court order for him to give them a blood sample, and they get their conviction.

As I said at the beginning of this review, it was refreshing to have an episode that wasn’t entirely concerned with a murder case: even though that’s what it became, it was enjoyable to see Holmes put his talents to use in pursuit of a different goal, and the ‘impregnable’ Leviathan was just the challenge he, and we as viewers, needed to go through at this stage in the season.

Likewise, the subplot was concise and reasonably enjoyable, once again involving Holmes interfering in Watson’s life: this time, he deduces that there is some tension between Watson and her mother, and invites himself to dinner with Watson and her family. He informs Watson’s mother, who is disapproving of her new career, that her job involves her ‘rebuilding lives from the ground up’, and that her chosen line of work is as noble, if not more so, than her previous one.

Watson’s mother turns up at the end of the episode, and tells her that it was never the nobility or lack thereof she disapproved of, it was the fact that her job never seemed to make her happy. However, she concedes that working with Holmes seems to make her happy, and she should consider staying on with him for longer. The episode ends with Holmes turning on the television to a news item about the mysterious benefactor who had an original Picasso delivered back to the gallery it was stolen from, supposedly suffering from a ‘guilty conscience’. Knowing Sherlock Holmes, I only have one reaction to that suggestion: as if.

Verdict: 9/10

A welcome shift out of the show’s comfort zone of strange murders, and a brief yet enjoyable subplot makes for a vast improvement on the previous episode. My only hope is that the show uses episodes such as this one and the earlier episode “Child Predator” as a benchmark, and improves on the general standard of episodes.