A nobleman in 1830's Finland has to contend with stuck-up relatives, his daughters' suitors, dark secrets from his family's past, mistaken identities and a haunted wing of his mansion.
Valentin Vaala's historical suspense film The Green Chamber of Linnaeus (1945) is based on the novel by Zacharias Topelius. In the story, set in the 1830s, Colonel Karl Littow, the lord of Linnainen Manor, and his daughters Anna and Ringa are proud of the immaculate history of their noble family. A foreign Count Spiegelberg, who is courting Anna, and the architect Kaarle Lithau, a minor member of the family, who is planning to renovate the building, come to visit the manor during the winter. Soon, the centuries-old secrets of the Linnainen estate and the Littow family threaten to be revealed to the estate's guests and hosts alike.
It is the end of the 1830s. The Littow family dominates the Linnaeus estate and boasts roots stretching back fourteen generations to the Baltic. Colonel Karl Littow tells his daughters Anna and Rinna about his ancestors and the obligations of nobility. Anna cherishes the family tradition and tells of having met a man in Helsinki called Lithau, who belongs to a lesser branch of the family. The conversation is overshadowed by a prophecy that the family will be in danger after the twelfth generation.
A foreign Count Spiegelberg arrives at the manor to buy a farm in Finland. Also arriving are relatives of the nearby Syrjäkoski house, the lady-in-waiting Winterloo, and her son, Captain Eusebius Winterloo, who is about to propose to another Linnaise daughter. The November ice attracts a skating competition and the captain bets that he will beat Rinna. In the middle of the race, a hailstorm comes up and swallows the skaters. The search for Rinna is in vain, but the lost girl meets a young man on the ice who says he is on his way to the castle and introduces himself as architect Kaarle Lithau. He escorts Rinka home safely and is welcomed by the colonel, who has been invited to the manor to design the renovations to the wing building. At dinnertime, the Captain also returns: after navigating his way home and also having a meal with the wallesmann, he dares to propose to Rinka in a merry drunken stupor.
The architect is accommodated in the Green Chamber, which has a popular reputation as a haunted house in a winged building inhabited only by the 90-year-old deaf Aunt Justina. Butler Holming tells Kaarle the dark history of the room: the Colonel's grandfather, the notorious Assistant Colonel Jaakko von Littow, built a separate wing to guard his wife, who, however, managed to have an affair with the young governess of Syrjäkoski, Kaarle's grandfather; the relationship resulted in a son, the lady was found dead in the garden, having fallen from the roof, and the Assistant Colonel himself was found on the roof, also breathless.
At night, Kaarle is awakened by the creaking of the door and sees an old woman in the doorway of a large oak cupboard, pointing to the drawers in the cupboard. One of the drawers falls to the floor and Kaarle finds a piece of paper, which turns out to be a confession by Jaakko von Littow from 1767. The assessor reveals that his position is based on deceit and injustice: he is in fact a despicable Lithau, whose mother has substituted the name of the orphaned Littow for that of the heir, and since his mother's confession and death he has been unable to renounce his artificial nobility; his wife's infidelity with the son of a foster brother, the real Littow, has been the punishment for his sins.
In the morning, Count Spiegelberg proposes to Anna from the colonel, who leaves the matter to his daughter: she flatly refuses. The Count leaves, offended, but soon returns to blackmail the Colonel over a 130-year-old Geldern trading house debt, saying he owns half a million bank rupees of the debt. The Colonel claims the debt has been settled, but the receipt has disappeared. Kaarle intervenes and tells him that the receipt is still there: the cupboard in the green chamber is broken open and the receipt is found. At the same time, the wallesmann arrives at the manor to search for the Count, who, according to the Riga police chief, is a known swindler from the Curia. The Count escapes and pursues the Viscount.
At Syrjäkoski, preparations are underway for Christmas: the Linnaeus people, Lieutenant Weder, and his sister Renata arrive as guests. In the middle of a picture show organized by the captain, an oil lamp fire escapes into the curtains: the flames spread quickly and, despite the attempts to extinguish the fire led by Kaarle, the house burns to the ground. Captain Winterloo is not worried but says that this has saved the wallesmann from a forced auction. At the Colonel's invitation, everyone leaves for safety in the castle.
On his way back, the Captain is joined in his sled by a Swiss governess from Linnais, Miss Adelaide, whom he falls in love with and proposes to. Kaarle tells Rinna he is going to Italy for two years and asks her permission to return to Linniste; she believes he and Anna have loved each other since they met in Helsinki. Unbeknownst to Rinna, the Colonel and Kaarle swap rooms for the night. At her father's bedside, Ringa thinks she is telling her father about Anna and Kaarle's love, and Kaarle does not reveal himself. The old woman in the Green Chamber appears to the Colonel, who is staying in the room, and demands that he right the wrong his ancestor has done. She also appears to Kaarle, whom she warns not to leave the castle.
In the morning, Kaarle is about to burn the confession of the Assessor when the Colonel interrupts him. Kaarle warns the Colonel not to read the paper and promises to leave his estate. The paper is burned and the men come to an understanding that the Littows and the Lithaus are of the same descent and are related. The Colonel promises his daughter to Kaarle if he succeeds in winning her love. To his mother's shock, Captain Winterloo announces that he will marry a governess, asks the colonel for a farm, and plans to set up a Swiss cheese dairy in the preserved barn at Syrjäkoski.
Kaarle meets Ringa and confesses his love for her, not Anna as she had thought. Ringa confesses her own love only after Anna has spoken her liberating words. In the green room, the young people are astonished to see a cupboard door open of its own accord: behind it opens a passage to Justina's room. "Take thy bride," the old woman says to Kaarle. "The curse has been lifted from our family and the dead can rest." Ringa presses happily against Kaarle's chest.
