Taken solely as an opportunity to see Saoirse Ronan and Margot Robbie — two of the most promising young actresses in film — square off as strategic, strong-willed and simultaneously stymied sisters from separate misters, Mary Queen of Scots is an unmitigated success.

Ronan is the title character and Robbie is Queen Elizabeth I— women trying to bridge centuries of belief systems and male oppression to blaze their trail in wrestling monarchy from men. Almost immediately, they establish a robust rivalry, crackling confrontational ideologies and, eventually, a commonality of crestfallen life and certain begrudging respect. Mary vociferously defends Elizabeth’s vigilant fear of revolt, dismissed as poppycock by men who would so easily slice Elizabeth’s throat for her seat. Meanwhile, the lonely and childless Elizabeth admires Mary’s unabashed pursuit of womanly passions. Even if Mary’s intimacy is most likely to breed only the opportunity for more betrayal, there was a scintilla of human connection to savor.

In the film, Mary and Elizabeth communicate only through written correspondence, save a speculative sequence from writer Beau Willimon (House of Cards) in a barn filled with billowing curtains. The fabric is thereto physically shield Elizabeth from Mary, establish plausible deniability that she would have so brazenly met her enemy face-to-face. But the scene more or less reminds you how diaphanous Mary Queen of Scots is when Robbie and Ronan don’t hold court — sometimes catching brisk, purposeful headwinds but more often knocked on its arse in the muddy moors.

Director Josie Rourke, making her leap from stage to film, mistakes her new canvas as something to crowd with shape after shape rather than shade fo nuance and meaning. So much of Mary reduces itself to a standard-issue sizzle reel for costume, hair and makeup, a cavalcade of XL- and XXL-sized duplicities and the stranding of fine character actors like Guy Pearce (who just resembles, and snivels like, Count Ruger from The Princess Bride) and David Tennant, whose John Knox the film envisions as a sort of Calvinist version of Tucker Carlson.

The film covers the span from 1561 to 1587. Yes, it asks us to believe a character played by Ronan — the very model of youthful Elizabethan-era portraiture — will age more years across this story than the actress has herself been alive. Born in 1542, Mary Stuart acceded to Scotland’s throne as a baby, generally squirreled away as her rule was relegated to regents. At 15, she became queen consort to France’s King Francis. By the time she returned home in 1560 at age 18, she was a widow and devout Catholic amid an increasingly rigid Protestant influence.

Elizabeth was cousin to Mary and daughter of King Henry VIII and Anne Boleyn, having assumed England’s throne as a Protestant in 1858. In her belief that she has a rightful claim to rule England, too, Mary initiates her challenge to Elizabeth. But Elizabeth is undaunted, eager to kill Mary’s hope sand send her comfortless back to the Old Continent. They launch a barrage of betrothal traps, blown-off summits, bombastic betrayals and, eventually, bloodshed.

Both actresses have perfected their stares of ferocity: Ronan in both joy and pain, in one scene literally trying to make a penis work for her for once, and not against her, in the sense of procreation and general usefulness; and Robbie during the constant whispering suspicions that she is somehow shirking her duties by not choosing the man who loves her (Joe Alwyn, in a similar whipping-boy woo object as he is in The Favourite) and establishing an heir.

While they share no shortage of “oh, snap!” moments or snickers at the showboating, preening and priggish-dolt men among them, Mary and Elizabeth come to realize they’ve both been damned from day one — Mary letting a vigilant guard of suspicion down for what she believes to be love and Elizabeth for defying expectation to sit down, be humble, smile politely and mark time until a man takes over. Safety in isolation is all these women could ever really hope for.

Regrettably, there are few striking visual images in Mary Queen of Scots to give counterweight, but several stand out. DuringMary’s wedding to her second husband, male courtiers sway like puppets in prescribed choreography that pleases her until it reveals the way they intend to proscribe her progress. Others invoke womanhood as the only claim either can carry — Mary’s menstrual blood scrubbed from her thighs and wrung into a chamber pot or the sight of Elizabeth, skin terraformed by a pox that seems to have rotted her from the inside out, reliant on wigs and garish makeup to retain any semblance of femininity. The best instance of Rourke’s visual storytelling is a hard cut from Elizabeth’s red floral arrangements splayed before her to Mary’s afterbirth. Perhaps an easily spilled bloodline is the most decorative pageantry of all.

Beyond those brief flashes, Mary Queen of Scots rarely shakes off the staid, stale traditions of the tony Elizabethan drama, and makes you appreciate even more the snap that The Favourite brings to a similar story of palace intrigue. Rourke and Willimon are simply too overeager to establish easy setups of point-counterpoint, allegiance and betrayal, over and over again, without really letting the fascinating idiosyncrasies of both women set a pace for their stories.

In all, you wonder if Rourke should have instead insisted on something with the smaller scale of the stage — letting these two tremendous actresses simply read their letters to one another, with light dramatization as necessary. Alas, much like the fate of the characters that Ronan and Robbie portray, they should be running the film but instead the film runs them.