A mystery torn from the pages of Scandinavian history, “Margrete: Queen of the North” becomes a taut and tense tale in the hands of Danish director Charlotte Sieling.

The filmmaker takes us back to an age when the mechanical clock had just been invented and serves up a classic “ticking clock” thriller of Byzantine intrigues, schemes and power-grabs in the early days of the Kalmar Union. “Margrete,” a “fiction inspired by real events,” is a history lesson wrapped in a damned entertaining movie.

For a stretch during the 14th through the early 16th centuries, the ever-warring Nordic states of Norway, Denmark and Sweden were ruled as one, largely thanks to the machinations and diplomatic wheeling and dealing of Queen Margrete.”Margrete” shows the lengths that queen was willing to go to in order to preserve her peaceful “perfect” union.

We meet Margrete (Queen Margaret I ) of Denmark on a battlefield, a child who watches her father King Valdemar wash the blood off his hands and off the signet ring that symbolizes his power. She grabs it for safe keeping. Even then, she had her eyes on a prize.

Over 40 years later, Margrete, “the greatest and most pious regent The North has ever known,” is in her glory. Trine Dyrholm plays the ruler and matriarch with a wily and self-satisfied but high-minded air, a woman who stands among the nobles of three nations at court and persuades them that this union has kept the peace, but that they all need to pitch in for an “army so strong the Germans will never dare attack us (in Danish).”

The “Teutonic Order” of Prussia has designs on their territories, the self-same invaders who worried Russia’s Ivan the Terrible a century later.

Margrete and her version of England’s various archbishop “chief ministers,” the ever-scheming head of the church, Peder (Søren Malling) who helped her see her dreams of “peace” and “prosperity” through unity come true. Her only son died some years before, but she adopted her great nephew Erik (Morten Hee Andersen) and as regent rules this new alliance with Erik as King.

Her answer to the Teutonic threat? Marry Erik to an English princess and form an alliance with England. The film’s creepiest scene introduces us to this little girl, Philippa, reciting her greetings at court to her much-older intended, in French. Paul Blackthorne brings an arched-eyebrow cunning to William Bourcier, the English crown’s negotiator on her behalf.

But just as these plans are set to fall into place, the Norwegian third of the alliance brings in a man claiming to be her son, the “dead” Olaf (Jakob Oftebro), with the Norwegians backing his claim to the throne over Erik.

Margrete and we in the audience smell a rat. As it was rumored she’d had the boy killed 15 years before, how could this be? If that was true, will she have to admit her guilt? If not, will she “recognize her own child,” if indeed this could be her long lost son?

Dyrholm lets us see the wheels turning as she tries to buy time, to keep a lid on all of this, and to figure out who is behind this sudden and sure-to-be-divisive appearance.

She’ll need a trusted noble (Simon J. Berger) and her favorite pirate named Roar (Linus James Nilsson), and maybe the aid of a hostage she rescued from the pirate’s clutches, Astrid (Agnes Westerlund Rase) whom she’s made a lady in waiting.

Can they uncover what’s really happening, reveal any plot and plotters that may be involved before the union breaks into factions and the whole enterprise dissolves, inviting foreign invasion?

Sieling, who directed the Danish drama “The Man,” as well as episodes of “Homeland” and ironically, “Queen of the South” in Hollywood, keeps the “public trial” of the would-be heir quiet and suspenseful and the behind-the-scenes scheming calm, deliberate and believable.

No one wants to be labeled a “tyrant” in this union. They’re all very concerned with appearances. Margrete keeps her own counsel, weighing and wondering, questioning and maneuvering. But Peder’s right when he says (the film is in Danish, Swedish, German, Norwegian and English) “His presence alone stirs chaos.”

The acting demonstrates a desire for self-control amongst the veteran statesman and woman, with all the fireworks coming from the newly-threatened king and the life-on-the-line man on trial, the would-be king.

Screen veteran Dyrholm (“A Royal Affair,” “In a Better World”) gives Margrete human layers beneath all that stoic statecraft. Dyrholm’s performanace maintains the story’s mystery, as if she herself is only warily asking questions she may not want the answers to.

And Sieling, who co-wrote the script, turns the third act into a nerve-wracking hunt for spies and treachery in an alliance that’s unraveling almost too fast for the “truth” to set anybody free, or send the villains to the gallows.

It all makes for a more riveting “what might have happened” mystery, a history lesson with a caveat and a damned entertaining one at that.

Rating: unrated, violence and nudity

Cast: Trine Dyrholm, Søren Malling, Morten Hee Andersen, Agnes Westerlund Rase, Jakob Oftebro, Simon J. Berger and Linus James Nilsson

Credits: Directed by Charlotte Sieling, scripted by Jesper Fink, Maya Ilsøe and Charlotte Sieling. A Samuel Goldwyn release.

Running time: 2:00