Back in 1998 when Simon Winchester’s book “The Professor and the Madman” was published, a film version was already imagined by quite a few reviewers, spurred on not only by the subject’s eminently dramatic trajectory but also by Mel Gibson’s much publicized interest. It seemed implausible: Gibson wasn’t the obvious choice for a Victorian-era biopic about James Murray, the man commissioned to bring the Oxford English Dictionary (OED) to life, but his involvement made it more likely that a dictionary compiler’s story could be packaged as something marketable to a general public. The star decided not to direct, novice filmmaker Farhad Safinia was brought in, and shooting wrapped in 2016. That’s when grumblings began to be heard publicly.

Officially, Safinia and Gibson wanted to add a few weeks of shooting at Oxford University to boost the authenticity (the lion’s share of the film was made in Dublin, with Trinity College standing in for Oxford). Voltage Picture’s CEO Nicolas Chartier balked, complaining they’d already gone over-budget and exceeded the agreed-upon running time. The star and his company Icon Prods. sued to prevent the film’s release but lost, and Safinia’s name was summarily removed from the credits, replaced by the fictive P.B. Sherman, in the version that quietly trickled into a few international markets in March, and which will be seen — or not — stateside on May 10.

For those that have been anticipating this curious, much-delayed oddity, the good news is that Gibson is fine; it’s everything else that doesn’t work. Given that Gibson is refusing to do publicity (and doubtless neither will co-star Sean Penn), the film’s chances of attracting audiences seem minuscule. But at least the possibility finally exists.

Only Safinia and his closest collaborators know just how much tinkering went on following his departure, but editing, alongside truly uninspired dialogue, are the picture’s biggest flaws. Penn’s over-acting was to be expected in the role of a schizophrenic made up like a cross between Tevye the Fiddler and Rasputin, but why is he the only one to age over the course of decades when no one else, including Murray’s kids, experiences the passage of time? A further problem lies in the way Safinia tries to make the work done by word-hounds seem kinetic, swerving the camera left and right during conversations in a flawed attempt to ensure audiences feel an energy that’s lacking in the screenplay.

Winchester’s telling of the improbable partnership between Murray and William Chester Minor made for a fascinating story, and despite heavy license in the cinematic retelling, the bare bones remain intriguing. Murray (Gibson) is a genius autodidact with a staggering fluency in more than a score of languages. Championed by Frederick Furnivall (Steve Coogan) to take over the stalled editorship of the dictionary, he overcomes significant academic snobbery to be awarded the prestigious position. Murray moves his wife (Jennifer Ehle, wasted) and family to Oxford, has a work shed built on his property, hires assistants, and begins to tackle the monumental assignment, which he estimates will take between five and seven years to complete.

While this is going on, an as-yet unrelated story is revealed: Paranoid American doctor Minor (Penn), in a delusional state, kills a man (Shane Noone). He’s declared insane and imprisoned at the Broadmoor psychiatric facility, where superintendent Richard Brayn (Stephen Dillane) realizes a Civil War trauma has triggered bouts of madness in this otherwise brilliant man of medicine. Minor’s sense of guilt leads him to offer money to the murdered man’s impoverished widow Eliza Merrett (Natalie Dormer), who at first refuses but then accepts the support since it’s better than being a streetwalker.

Murray is meanwhile working hard on the dictionary with his assistants, but they find themselves hopelessly behind and undermined by a cabal led by the publisher, Philip Lyttelton Gell (Laurence Fox, lacking even an iota of nuance), and board member Benjamin Jowett (Anthony Andrews), the latter grossly mischaracterized. A general call is put out for freelance contributors to submit word origins, and Minor maniacally begins bombarding Murray with references that advance the dictionary to a considerable degree. The editor has no idea his most valued helpmate is criminally insane until he travels to Broadmoor to thank him. The meeting goes well, kind-hearted Murray is sympathetic, and the two continue an epistolary collaboration that adds considerable meat to the skeleton of the OED.

A costume drama about a dictionary editor and a crazy man could hardly have gotten a green light without some romance, so the scriptwriters have Eliza and Minor fall in love in an unlikely subplot that wildly extrapolates from Winchester’s conjecture. At least the thwarted love story is a stab at giving a female character some kind of presence, since the screenplay hasn’t a clue what to do with Murray’s wife Ada, indiscriminately having her chafe at her husband’s devotion to his work and then flipping to portray her as the ideal supportive companion.

Time is oddly telescoped, though this could be the fault of sloppy editing following Safinia’s departure. The same excuse can’t be used for many other serious flaws, such as Murray’s ludicrously late realization that John Milton would be a useful source for word usage, or a painful scene in which Minor teaches the illiterate Eliza how to read while walking up and down Broadmoor gardens. Penn’s tendency to play to the gallery when not guided by a strong director is on full display, sharply contrasted with Gibson’s modest turn as the self-effacing Scotsman. For reasons best known to himself, Anthony Andrews seems hell-bent on channeling late-period John Gielgud in a performance composed entirely of mannerisms and no substance.

Given the number of historical inventions, perhaps pretending Trinity College is Oxford wasn’t really such a traitorous decision. Far worse is the wearying score whose omnipresence leads attentive viewers to the conclusion that the producers didn’t trust the images and felt sappy music was the only way to rouse emotions. Curiously, the Voltage website still lists Safinia as director.