The two youngest nominees in last year's Best Actress Oscar field come together in Mary Queen of Scots, a film whose talented leads, Christmastime opening and historical subject matter suggest a major awards contender but whose middling execution and unproven personnel behind the camera explain why it is unlikely to feature in anything but maybe a technical category or two.

Saoirse Ronan plays the titular sixteenth century monarch, whose claim to the throne of England is described in opening text as "strong." At the moment, that crown is worn by Queen Elizabeth I (Margot Robbie), Mary's cousin. Mary is Catholic, Elizabeth is Protestant, and in the immediate wake of the English Reformation, that is a big deal.

Mary has already been widowed by the time we meet her, but neither she nor Elizabeth has any heirs, which is also a big deal in royal circles. The two actresses do not share the screen until the film's (apparently invented) pentultimate scene. They communicate through those who counsel. There is obvious tension between the two strong-willed women, though questions surrounding succession remain up in the air amidst surprising civility.

Mary does take a husband in Henry (Jack Lowden), whom she catches on their wedding night sleeping with her friend and confidante, the musical Italian courtier David Rizzio (Ismael Cruz Córdova). Mary is not much troubled by her husband's apparent homosexuality, needing him only to impregnate her, which he does in time.

Her reign is a fragile one and when Henry and others carry out some instant justice against Rizzio over accusations of adultery, Scotland's ruler begins to unravel. Led by John Knox (David Tennant), the Protestants are firmly against Mary's papist leanings. And the long-distance relations between England and Scotland's cousin governments are cause for concern, as others around the throne position themselves for advancement, including Henry's father.

Adapting the early 2000s book Queen of Scots: The True Life of Mary Stuart by British historian John Guy, the screenplay by Beau Willimon ("House of Cards", The Ides of March) fails to bowl us over. Our attention is mostly fixed on Mary, whose reign is shaped primarily by her need to procreate which is addressed pretty quickly. Beyond that, we simply watch as the queen has a falling out with her half-brother James (James McArdle) and scrambles to maintain her claim to the throne and have it passed on to her son.

Ronan is a great actor. Her first Oscar nomination came half a lifetime ago for 2007's Atonement, and it's already clear that she is the rare child actor who graduates to movie stardom in adulthood. She's actually been bouncing around between adult and child roles for a few years now, being responsible for much of the success of two of the decade's best films in the romantic drama Brooklyn and last year's unanimously heralded high school comedy Lady Bird. The reason I say this is because it's tough to imagine anyone else being able to elevate the script by Willimon and the direction by stage-seasoned first-timer Josie Rourke beyond the modest heights they reach here. Ronan is almost strong enough to advocate her earning a fourth Oscar nomination well before her 25th birthday, but the film just isn't good enough to vie for anything greater than perhaps Costume Design and Hair & Makeup contention.

Robbie has far less screentime than you might expect given the marketing which makes the actresses look like co-leads. In contrast to Ronan's prominently accentuated natural beauty, Robbie gets to play against type here and look less than attractive with a subtle prosthetic nose and a litany of smallpox scars. We can dispute that going frumpy is the way for glamorous actresses to get recognized with awards, but Robbie's nomination for I, Tonya last year and Best Actress wins for the likes of Charlize Theron (Monster) and Nicole Kidman (The Hours) suggest there is credeence to that theory. The role of Elizabeth I isn't as juicy as you want it to be and Robbie disappears for large stretches before finally getting a face to face with our heroine while looking a bit like Helena Bonham Carter's Queen of Red Hearts in Tim Burton's Alice in Wonderland.

There is a long tradition of costume dramas being recognized at the Oscars. But this year that role appears to be filled by Yorgos Lanthimos' The Favourite, a more sumptuous and offbeat production that hasn't left my fellow critics as cold as it did me. Rourke does a decent job in her film debut, and the movie looks nice with its shots of rambling hills, but there just isn't enough here to move or compel, not even with the color-blind casting and seemingly anachronistic attempts to find modern views of gender and sexuality in the material.