Margrete: Queen of the North opens in blood, with the young princess borne by the King through the battlefield after he wins the 1361 Battle of Visby. Years later Margrete, now Queen, has negotiated a peace union between Denmark, Sweden and Norway, whose testy alliance has strengthened the north against outsiders, including Germany.

She rules through her adopted son, King Erik, and is brokering a marriage between him and the juvenile English princess Philippa, daughter of Henry IV. The terms are still to be decided but the union will make the north unassailable, the Queen thinks.

Then, a bombshell. A man calling himself Oluf, the Queen’s true son who died from poisoning 15 years earlier, arrives at court to claim the throne. He is imprisoned and Margrete denies him publicly, but she isn’t sure. She questions her confidantes and can find no one who actually saw her son dead. What she does learn is who engineered his removal.

This intrigue sets the wheels of power spinning and we watch a marvellous unravelling as Margrete tries to juggle maternal grief and doubt with the political imperatives of staying in command. She visits Oluf at night in his cell and questions him in a public hearing. He hums a lullaby they both know. It all seems to stack up.

Actor Trine Dyrholm – who appears in another Scandinavian Film Festival highlight, A Matter of Trust – is unfailingly brilliant as the measured, ambitious Queen who must spill blood to save the peace. Margrete rules through Erik, who she adopted as a pale boy from Pomerania; she invested everything in making him her King. How much should it matter whether Oluf’s claims are true or not?

This is one of the most expensive Danish movies ever made and it is beautifully filmed, with the gloomy castle interiors lit by candles and the heaviness of royal gold. It moves at a stately pace as the drama deepens and the Queen is alternately pitted against the son she adopted and the one who returned.

Familiar faces in the splendid cast include Søren Malling as the Queen’s confidante Peder, a man of the church with secrets, and Morton Hee Andersen as the entitled Erik.

Director Charlotte Sieling – whose history includes episodes of Unit One, Borgen, and the Mexican drug thriller Queen of the South – guides us through the labyrinthian politics as we follow Margrete’s anguish as a mother and as Queen.

Margrete: Queen of the North is screening as part of the Scandinavian Film Festival, which is at Palace Nova Eastend until August 10.