Sherlock's Most Underrated Episode Is Also The Hardest To Watch

Published Aug 2, 2026, 9:30 AM EDT Adrienne Tyler is a movies & TV features writer, with a focus on horror. She has written for Netflix, FanSided, & more. She was a regular guest on the Netfreaks podcast and was a YouTuber at some point. Guillermo del Toro said “hi” to her once. Mentions of death, murder, and abuse. The BBC’s Sherlock has some great episodes, but also some underrated ones, and one of the latter is also the show’s hardest episode to watch. As one of the most popular literary characters, Sherlock Holmes has been adapted to all types of media for decades. In recent years, Holmes and company have found great success on TV, especially with modern adaptations that brought them to the present-day. Thanks to this, viewers got to see the Great Detective use modern technology and deal with current social issues. The most notable modern adaptation of Sherlock Holmes is the BBC’s Sherlock, created by Mark Gatiss and Steven Moffat. Throughout four short seasons, Sherlock followed the Great Detective (Benedict Cumberbatch) and Watson (Martin Freeman) as they investigated a variety of cases, some of them quite disturbing. Sherlock had a strong start in its first two seasons, but, unfortunately, the final two saw a drastic decline in quality. Still, Sherlock is one of the best detective TV shows of all time. However, seasons 3 and 4 had some underrated episodes, one of them being “The Lying Detective.” Loosely based on the short story “The Adventure of the Dying Detective”, the episode introduced villain Culverton Smith (Toby Jones), who, unfortunately, was a one-episode antagonist. Still, he left an indelible mark and made “The Lying Detective” the show’s most underrated episode, but it’s also the hardest one to watch. "The Lying Detective" Is The Highlight Of Sherlock's Mixed Fourth Season “The Lying Detective” takes place after the death of Mary Morstan (Amanda Abbington), Watson’s wife, and as a result, Watson and Holmes have distanced themselves. While Watson returns to therapy as he mourns his wife, Holmes has isolated himself at Baker Street and started consuming drugs again. Holmes is approached by Faith Smith, the daughter of entrepreneur and philanthropist Culverton Smith, who confessed to her and others that he was going to kill someone. However, Smith used a serum on them that inhibits memory. After some hesitation, Holmes takes on the case and drags Watson into it, but facing Smith is a lot more terrifying than it seems. “The Lying Detective” is the second episode of Sherlock season 4, and while it’s definitely the worst season of the show (in large part thanks to the series finale), this episode is the one highlight of it. “The Lying Detective” is the closest season 4 got to the tone and style of the first two seasons, with a complex case, a terrifying antagonist, drama between Holmes and Watson, and Holmes surprising the audience and characters with his plans. Culverton Smith is one of Sherlock’s best villains and a strong contender to take Moriarty’s (Andrew Scott) place, along with season 3’s Charles Augustus Magnussen (Lars Mikkelsen). Smith could have brought a lot more to the show had he been given the chance of a bigger arc beyond his debut episode, and his dynamic with Holmes was what the show needed after some messy episodes. Why Sherlock's "The Lying Detective" Is So Terrifying Culverton Smith is based on a fictional character and a real-life criminal. Smith is based on the character of the same name from Sir Arthur Conan Doyle’s “The Adventure of the Dying Detective.” The original version of Smith is also a murderer, being the one responsible for his nephew’s death and for trying to kill Holmes, too. Smith only shows up in “The Adventure of the Dying Detective”, so more details about him are unknown. To flesh out the character, and perhaps to also make him more terrifying by linking him to the real world, Sherlock’s Culverton Smith was loosely based on Jimmy Savile and his crimes. The once-celebrated British entertainer was revealed to have been a prolific predatory sex offender in 2012, a year after Savile’s death. Like Savile, Smith hid behind his image of a charming philanthropist while, behind the scenes, he was committing horrible crimes. Savile used his charitable work to commit his many crimes, as did Smith, who operated a hospital through which he had access to his victims. To the British audience, Smith’s and Savile’s parallels were clear and unsettling, but they might not have been obvious to those who didn’t know about Savile’s crimes. “The Lying Detective” is Sherlock’s most underrated episode, overshadowed by the mess that was season 4, but it might be tough for some to rewatch it. Release Date 2010 - 2017-00-00 Network BBC One Showrunner Steven Moffat Directors Paul McGuigan, Nick Hurran, Euros Lyn, Jeremy Lovering, Rachel Talalay, Colm McCarthy, Toby Haynes Writers Steve Thompson Franchise(s) Sherlock Holmes Creator(s) Mark Gatiss, Steven Moffat