Not until I watched “Firebrand” did I think the sight of Jude Law’s naked behind could cause me to recoil rather than rejoice. Playing a late-career Henry VIII, Law is all rutting buttocks and barely mobile bulk, an obese, paranoid ruler with a weeping leg wound where maggots wriggle in ecstatic close-up. Law (and his director, Karim Aïnouz) might be laying it on thick, but his grotesque tyrant is the only thing lifting this dreary, ahistoric drama out of its narrative doldrums.

Adapted from Elizabeth Fremantle’s 2012 novel, “Queen’s Gambit,” “Firebrand” seeks to highlight Henry’s sixth and last wife, Katherine Parr (Alicia Vikander), the only spouse to outlive the infamous king. Studious and devout, Parr conceals her Protestant sympathies while arguing in favor of women’s education and an English-language Bible. Her clandestine support for the poet and Protestant preacher Anne Askew (Erin Doherty), however, almost proves fatal when she’s accused of heresy by an oily bishop (Simon Russell Beale).

Unfolding in and around Whitehall Palace in 1547, the movie is lavishly, oppressively costumed, the actors imprisoned by fabric and a screenplay that plays fast and loose with the historical record. A plummy voice-over describes Henry’s kingdom as “blood-soaked” and “plague-ridden,” though we see little of either plasma or pustules. What we see is a queen whose downcast demeanor speaks less of a firebrand than of a wife placating a husband who isn’t above spousal decapitation if a younger, saucier option should wiggle past.

That Parr deserves a spotlight is easily argued. But the woman who believed herself chosen by God to influence the King is, despite Vikander’s skills, ill-served by this meandering, glum picture. So much so that, in just two brief appearances, Doherty’s vivid portrayal of the reformist Askew makes us wonder whom the film’s title is really memorializing.

Firebrand
Rated R for spousal abuse and celebrity skin. Running time: 2 hours. In theaters.