Some characters grab a hold of the collective psyche to be reincarnated over and over again. First created in 1887 for A Study in Scarlet by Sir Arthur Conan Doyle, Sherlock Holmes originally appeared in four novels, 56 short stories, and overall, a staggering 25,000 adaptations spanning literature, the stage, film, and television. The Guinness World Records has even awarded Holmes the title of most portrayed literary human character in film and television history.

While there’ve been memorable Sherlocks over the past decade — Robert Downey Jr. on the big screen and Jonny Lee Miller on the small in Elementary — one of the most impactful on the canon of late was BBC One’s Sherlock. With just four "series" (the BBC’s version of seasons) consisting of 13 episodes (plus an extended trailer and un-aired alternate pilot), the moody British crime drama featured Benedict Cumberbatch (Doctor Strange) in arguably his breakout role as the eccentric Sherlock, and Martin Freeman (The Hobbit, Black Panther) as Dr. John Watson.

Updating a classic

Paying homage to what audiences love about a certain character or story is as crucial as seamlessly layering in the unexpected that’ll hook them into the new concept. Where Sherlock shines is in not updating the tropes, characters and scenarios that make the world so beloved to the point where it’s unrecognizable. A fine line to walk when updating a classic for contemporary audiences. Gone is Victorian England, in its place present-day London and along with it, advanced forensics that weren’t around in the 19^th century. While this improvement helps solve crimes in Sherlock, the show ensures the titular character is still the one doing the majority of the solving as the one person who can see what others can’t.

For his part, Watson is recently returned from a tour in Afghanistan as part of the Royal Army Medical Corps when the series premiered in 2010. Eerily, Doyle’s original Watson had just returned from Afghanistan in the 1880s version, and thus the writers and Freeman simultaneously updated the classic character as well as drew direct parallels to the present time of the show. Watson struggles with PTSD and finds as much catharsis in solving mysteries with Sherlock as he does solace in writing his blog about their crime-fighting adventures.

Another classic Sherlock character to receive an update is that of his arch enemy, Moriarty, who in Sherlock is cunningly played by Andrew Scott (Fleabag). And because a hero is only as good as his villains, Moriarty and his compatriots need to shine. The writers achieved that in spades by making him, along with other fan favorites such as Irene Adler (Lara Pulver) multifaceted.

But where Sherlock explored somewhat new territory is with Mr. and Mrs. Holmes. The very "normal" couple is curiously at odds with what we would expect of the parents of Sherlock and Mycroft Holmes. Even more curious is the couple’s casting: Cumberbatch’s own parents, Timothy Carlton and Wanda Ventham. The thing with exploring new territory in a familiar story is it keeps it interesting for not only the audience watching, but the actors as well.

And of course one cannot speak of Sherlock Holmes without recalling his infamous line, "Elementary, my dear Watson." Which on Sherlock was only uttered once, in the show’s Christmas episode "The Abominable Bride." Most likely also not a coincidence, the one episode in the show's run that features a literal throwback to 1890s London and the original Sherlock aesthetic. The lesson for screenwriters here? When working with IP, be respectful, but take the chance of making it your own, too.

Technology and twists

Not only do Sherlock and Watson get to use modern-day science to solve crimes, the show’s creators infuse moments of Sherlock with additional visual delights superimposed on the action — Sherlock deducing whodunnit through literal connections, text messages floating across the screen, and character memories rewinding — to up the visual ante.

Another tactic the writers used to up the ante — and a key to success for any murder mystery — is adding plenty of twists. While part of the fun can be trying to guess the ending, if the show’s writers had followed every Sherlock story to the letter, no doubt even fans of the original would be bored. Again, finding the balance between familiarity and original content can make all the difference for the success of a script. As are the bits of levity the writers infused into the darkness of Sherlock’s world. The aesthetic is cold and moody, yet the witty (if unintentional) banter between partners Sherlock and Watson tend to make the moments that matter hit all the harder.

In Retrospect

The Mark Gatiss (who also played Mycroft) and Steven Moffat-created show was undoubtedly a hit on both sides of the pond, not only among Sherlock Holmes fans, but critics and audiences who are still hoping for a fifth series... if Sherlock and Watson ever stop playing in the Marvel Cinematic Universe. Because who doesn’t love a good game of seven degrees of separation?

Screenwriters can peruse three scripts from series one, "A Study in Pink," "The Blind Banker," and "The Great Game," (available here) to see how the page translates to the show we came to know and love.