The framing of Bill Condon’s Mr Holmes is, on the face of it, rather peculiar. Adapted from Mitch Cullin’s “A Slight Trick of the Mind”, it tells a fictional tale about a fictional character – Sherlock Holmes (Ian McKellen) – yet it’s presented as though it were a biopic about the final years of a renowned celebrity, à la Mr Turner. In the Mr Holmes’ opening minutes, that comparison feels especially apt, what with the stately titles, the dignified classical score and McKellen’s performance; his age exaggerated with liver spots and an unsteady gait, his grumbling and grunting feels like a subtler version of Spall’s performance in Mike Leigh’s 2014 biopic.

Mr Holmes presents Sherlock Holmes as a historical figure within its diegesis. In this world, the books written about him were authored by his partner Watson, not Conan Doyle. In 1947, decades after retiring, Holmes is an irritable curmudgeon who resents his lingering fame and the “fictional licence” Watson took in his novels (he prefers a good cigar to a pipe, for example). It’s only as the film progresses – and splits off into two additional timelines, one centring on Holmes’ final case shortly after the end of the Great War, the second in Hiroshima shortly after the end of the Second Wold War – that the conflation of fact and fiction is revealed to be integral to the very purpose of Mr Holmes.

“Fiction is worthless,” intones Holmes. “I prefer fact.” But the screenplay – adapted from Cullin’s novel by Jeffrey Hatcher – refuses to draw well-defined boundaries between the two. In 1947, Holmes is increasingly beset by dementia and struggles to retain his dwindling memories. The veracity of the flashbacks to earlier timelines, implicitly drawn from his recollections, therefore comes into question. Are these factual accounts (of a fictional character) or simply another layer of fabrication, imagined by a man plugging the gaps in his memory with fragments of fiction? Does this distinction even matter, particularly in a film that some audiences may not even recognise as fictional in the first place?

Rather than provide an explicit answer to such questions, Mr Holmes uses this ambiguity to reflect upon remorse and the weight of history. At Holmes’ country estate, he is cared for by his housekeeper, Mrs Munro (Laura Linney) and her son, Roger (Milo Parker). They have their own experience of loss – Roger’s father died in the war – and the bond that Holmes forms with the young Roger becomes the central relationship of the film. Sharing stories of his final case with Roger, Holmes lectures him thusly: “Death, mourning, grief – they are all commonplace. Logic is rare.” Yet these commonplace concerns provide the backbone of the narrative; while Holmes’ trademark prickliness and preternatural gifts of observation are present, the slender mysteries offered by the film’s three volumes are largely incidental. Mr Holmes is less interested in solving puzzles, more interested in examining the ghosts of fiction, the spectres of history, the “invisible stories” we tell.

Each of the film’s three stories carry their own burden of death, mourning and grief. Holmes’ final case – involving glass armonica lessons and a suspicious husband – initially promise a murder mystery before revealing its primary concerns to be the impossible implacability of grief and the inadequacy of reason. His trip to Japan begins as a simple quest to obtain more prickly ash (or “ashy prick”, as his doctor (Roger Allam) quips) to assuage the retired detective’s encroaching senility, but proves to be a reflection on mourning. And the shadow of death – of Holmes’ fast-perishing bees, of Mrs Munro’s absent husband, of Holmes’ own mortality – hangs over the mid-century storyline. Taking cumulatively, it’s clear that the logic to which Holmes clings is insufficient, and the salving qualities of fiction are worth treasuring.

Condon – returning to more ‘prestigious’ pictures after helming the final films of the Twilight franchise – produces handsome but undistinguished work from the director’s chair. In concert with cinematographer Tobias A. Schliessler, he creates images that are consistent with the sense of a respectable British biopic, with crisp lighting and browns dominating the palette. Yet there’s nothing distinctive here; this is the sort of film where every flashback is singled by a slow zoom-in on McKellen looking reflective, because That’s How It’s Done.

McKellen acquits himself well in the lead role. I found his early grumbling and grousing overly broad, but you get the sense as the film progresses that it’s a performance on the part of Holmes – a way of shutting people out – rather than McKellen himself overstepping the line. He’s not entirely relegated to ‘grumpy old dude’, either; the London flashbacks demonstrate his grace and dignity as a proper English gentleman, top hat and all. He does commendable work to ensure that the grandfatherly relationship he forms with Roger avoids coming across as clichéd; though, of course, Milo Parker deserves some credit here as well (in only his second acting role! Keep an eye on this one.)

As Mr Holmes advanced towards its conclusion, progressively unfolding the particulars of its plot, I began to experience an odd anxiety that its low key reflection on fact and fiction would be derailed by an insistence on a ‘neat’ narrative – much like Conan Doyle’s novels, whose offhand observations accumulate and converge into a complete conclusion. That anxiety proved largely unfounded, though I couldn’t help wondering as I left the cinema whether there was an unspoken plot twist lurking underneath, especially given the unreliability of Holmes’ memories. Maybe I’m simply reading too much into the resemblance between Laura Linney and Hattie Morahan. Or maybe I’m just filling in the blanks with my own fiction, recalibrating any uncertainty into a more satisfying, less ambiguous conclusion. Perhaps, like Mr Holmes himself, I have simply shaped my own experience from a combination of facts and fictions.