It can be a strange thing these days: some actors either play a role so many times or play it so effectively once that it becomes nearly impossible to fill the shoes, impossible to recast the role or to even imagine recasting the role. The former scenario – where an actor owns a role by performing it over multiple films – is more and more common now that the shared universe and neverending saga models are actually viable. Robert Downey Jr. and Hugh Jackman had the advantage of being the first to play Tony Stark and Wolverine in their respective franchises, but it’s still damn difficult to imagine what those cinema characters will look like ten years from now once Messrs. Downey and Jackman age out of the parts.

The latter camp – those who own a role after only a single performance – is more interesting, at least when the role we’re considering is that of Sherlock Holmes. The great deerstalker-capped detective has been played by hundreds of actors onscreen, notably by the likes of Basil Rathbone, Christopher Lee, Roger Moore (in Sherlock Holmes in New York), and the aforementioned Downey Jr. in the most recent feature adaptations. Peter O’Toole voiced the character in a series of animated shorts in the early ’80s, Ian McKellen will portray him in 2015’s Mr. Holmes, and Benedict Cumberbatch plays Sexy Holmes in the BBC show Sherlock. Jeremy Brett’s decade in the role spanning four separate series is certainly one of the most interesting turns – Brett’s health declined noticeably as each series progressed, and his time in the role ended up charting a tragic bearing through his final years.

So which actor owns Sherlock? Or is it the other way around – which actor was owned by Sherlock? Tough to say, and impossible to ever answer definitively. Despite the tagline plastered across the DVD cover for 1979’s Murder by Decree – which deems it THE BEST SHERLOCK HOLMES MOVIE EVER MADE – the least likely candidate would ostensibly be Christopher Plummer. Murder by Decree falls smack dab in the middle of Sherlock-dom, halfway between the stuffy, prim and proper Holmeses of old and the modern, edgy, “cool” Holmeses that generally grace our screens today. Plummer’s Holmes certainly hews closer to the old proper detective, but the in-betweenness of Murder by Decree stands as the reason it’s one of the most overlooked Sherlock films. Likewise, Plummer’s take on the detective has fallen into relative obscurity.

But that traditional look and feel paired with the healthy dose of modernity Plummer manages to inject into the role shouldn’t be overlooked. It also launches his Holmes – already compelling enough as he deals with the case of Jack the Ripper – into the running for that impossible-to-attain prize of Best Sherlock. James Mason is well-suited (if a bit old) for the part of Watson, and other famous faces include those of Donald Sutherland and John Gielgud. Great actors all, but Plummer puts them to shame in exactly the way that a good Sherlock should. He’s a Sherlock who’s comfortable in himself – who may have, in fact, complete confidence in only himself – and because of that his every move is somehow effortless. Murder by Decree is kindred to the best Holmes yarns in that it seems everyone is running around struggling to even comprehend what’s going on while Holmes can only smile at the futility of their efforts.

Conversely, Decree isn’t afraid to show a vulnerable, struggling Sherlock either. His climactic fistfight with the Ripper ends in the latter’s demise, but it’s clear that the exhausted and battered Sherlock would have saved his life if he had the strength. One of the Ripper’s victims is a young woman that Holmes had come into contact with at one point, and the blame he places upon himself for her death humanizes his character past all of the cold-and-calculating stuff that Sherlock is usually associated with. He is, at times, a vengeful Sherlock too – stating to a suspect of the aforementioned woman near the midpoint of the film, “If she dies and you come under my hand, expect no mercy.”

These “human” characteristics actually probably have more in common with Downey Jr.’s Sherlock than anyone else’s, although the comparisons begin and end there. Downey is disheveled, manic, highly eccentric, and constantly bickering with Watson – all of which work well for his particular incarnation. Plummer’s Sherlock is refined, accepted by society, and his relationship with Watson is much deeper than the banter-based Downey version. Sherlock and Watson laugh and joke as old friends, they assist each other in times of need, they exchange ideas and, yes, they bicker. Sherlock frequently launches into monologues that leave Watson in the intellectual dust. If it’s impossible to argue that Plummer is the best Sherlock, then surely we can at least assert that Murder by Decree gives the lead actor the most meat to chew on, from scenes with Watson to the personal demons to the case itself to the way they all tie together.

Lastly, one of the best moments in Sherlock history comes in this film, although it’s one of the more subtle character moments that you’re likely to appreciate more if you’re sold 100% (as I was) on Plummer’s incarnation of the detective. There’s a frequent stylistic trope that occurs throughout Decree consisting of a slow, slow, painfully slow zoom on Sherlock’s face as he internalizes dialogue, the image of his face gradually fading into a visual depiction of what he’s describing. It works brilliantly in the “reveal all” scenes, and then once the telling is told we slowly fade and zoom back out and return to Sherlock’s mug. There’s one scene that occurs midway through the film, after this trope has been established three or four times, wherein Sherlock sits across from Donald Sutherland’s fortunetelling character Mr. Lees (a real figure also featured in the suspiciously-similar From Hell). With great urgency, Lees speaks of his visions and premonitions and then says to Sherlock, “Mr. Holmes, I have the strongest intuition concerning you. I sense a danger, close and threatening.” Then we get the zoom, the slow, slow, painfully slow zoom into Sherlock’s visage, we’re expecting the fade out, and then…Sherlock simply sits back and smiles. “I have a sense of it myself,” he says.

For reasons I can’t possibly hope to explain, that’s Sherlock.