There’s presumably more heated drama behind the screen than there is upon it in “Effie Gray,” a literate, lovingly mounted and exceedingly well-behaved historical biopic that has sidled into British theaters after two years of less polite legal conflicts. Emma Thompson’s first adult-oriented film screenplay since her Oscar-winning work on “Sense and Sensibility” finds a fascinating human subject in the title character — the socially and sexually suppressed wife of leading Victorian art critic John Ruskin — but this admirable, watercolor-delicate tale of individual feminist emancipation never quite blooms into living color, hampered by spotty casting and Richard Laxton’s overly deliberate direction. Lush production values and name players — notably a conscientious Dakota Fanning in the lead — guarantee international exposure, but commercial prospects are as muted as the film itself.

The pic’s closing credits rather pointedly refer to the “original screenplay by Emma Thompson,” a still-piqued rejoinder to a pair of plagiarism lawsuits from previous writers who attempted to bring Euphemia Chalmers Gray’s life story to the screen. The suits may have been unsuccessful, but a measure of damage has been done: Thompson, for whom this was once a passion project, has opted out of doing any publicity for the film’s U.K. release. Yet it’d be a shame if this ambitious if under-realized film were to be written off as mere folly. It’s not hard to see why multiple writers were attracted to a story in which aberrant sexuality and full-bodied yearning roil beneath its heavily clothed surface, and Thompson’s screenplay dissects the cruel curiosities of the era’s gender politics with commendable tact and intelligence.

If nothing else, “Effie Gray” would merit appraisal as a fortuitously timed companion piece to Mike Leigh’s soon-to-be-released “Mr. Turner,” in which disenfranchised women also suffer at the inattentive hands of Victorian art-scene titans. Ruskin, a fervent champion of J.M.W. Turner, features in both films in very different guises: A precocious prig in Leigh’s film, he’s imagined by Thompson as a more reserved, coldly passive-aggressive figure. Furthermore, the real-life Ruskin was only nine years older than his bride; he’s played here by Thompson’s husband, Greg Wise, who is 28 years Fanning’s senior. Wise’s ostensible miscasting has the effect of making Gray’s position all the more vulnerable, virtually that of a child amid hostile elders.

That Ruskin is himself presented as something of a man-boy, still helplessly subservient to his domineering parents, is a character detail made even less palatable by Wise’s middle-aged countenance. Infantilized in a very different way from his 19-year-old wife, he never seems an appropriate suitor for her at any stage of their relationship. Given that his viciously curt mother (played by Julie Walters as a kind of unholy hybrid of Mrs. Danvers and Mrs. Bates) disapproves of the match from the get-go, it’s not obvious to viewers what motivates this union between cosseted Englishman and grounded Scotswoman. We learn eventually that it’s not any kind of sexual impulse: Ruskin could not once bring himself to touch his wife over the course of their six-year marriage. This abnormal physical neglect, combined with largely tacit psychological abuse, drives Gray conveniently into the brawnily sympathetic arms of Ruskin’s young protege, painter John Everett Millais (Tom Sturridge).

The elements are therefore in place for a lurid slab of corseted soap opera, though Thompson and TV-schooled helmer Laxton (who has since directed “Burton and Taylor” for the BBC) largely eschew melodrama in favor of chaste, chamber-style character study, with Gray’s physical and mental deterioration methodically dramatized by incremental degrees. Her very private personal breakdown is of more interest to the filmmakers than the landmark annulment case that ultimately dissolved her marriage or her happier subsequent romance with Millais, both of which might seem more traditional points of dramatic emphasis.

Though the film’s dim, artfully mildewed shooting style — even Venice, in Gray’s constricted world, is practically as dank as the Highlands — supports this more intimate focus, Laxton and editor Kate Williams do little to concentrate the material, reinscribing established settings and character dynamics to stultifying effect. Neither an expansive history nor an intensive individual portrait, the middle-path result is speckled with intriguing political nuance, but feels lengthy and tonally oppressive at 108 minutes.

It’s Thompson herself who provides the pic’s scant interludes of humor with her reliably warm presence as Lady Eastwick, a liberal-minded society wife who inspires Gray to stand up to her husband. Beyond her few scenes, viewers’ emotional engagement with the film will hinge heavily on their response to Fanning’s studious but low-temperature turn as the heroine, whom she plays with dedicated attention to the physicality and propriety of women in the era. It’s a performance bravely shorn of 21st-century perspective, while immense credit must go to the hair and makeup team for accentuating the actress’s milkily spooked, perfectly period-appropriate features.

Then again, practically every member of the film’s overqualified cast — charismatic performers given far too little to do range from Claudia Cardinale as a sympathetic Italian chaperone to Russell Tovey as the Ruskins’ stifled butler — is lit and styled like a figure in one of Ruskin’s favored paintings, ones on which the paint has long gone dry. Using gauzy lighting effects with very different intent from the chintzy nostalgia he achieved in “Lee Daniels’ The Butler,” d.p. Andrew Dunn is working in no less painterly a mode than Dick Pope in “Mr. Turner,” though the darker, damper palette here contributes an apt sense of shuttered internal decay.

James Merifield’s production design and, in particular, Ruth Myers’ remarkable costumes work toward a similar purpose, often saying as much with simple textural contrasts as with more emphatic color shifts. There are acres of implied human difference between the open-bodiced satin sweep of Lady Eastwick’s gowns and the abstruse, aging woollen layers of Effie Gray’s wardrobe — a suffocating chrysalis of shawls from which this attractive but timid film brings her only to the barest brink of escape.