Composer Lewis Dodd arrives in the Austrian Alps to visit his friend and mentor Albert Sanger, who lives there with his unconventional family. On the journey, he meets Trigorin, a fan of Sanger, also on his way to see him. On arrival, Lewis is greeted enthusiastically by two of Sanger's daughters, teenagers Tessa and Pauline, and they all go up to the family home, Karindehütte. There, Trigorin is introduced to the rest of the family, including Sanger's third partner, Linda, who is clearly unpopular with the daughters from his earlier relationships.

The atmosphere in the Sanger house is jolly and Lewis is clearly greatly loved there. Another of the daughters, Toni, is seen with Ike, a rich benefactor and supporter of the Sangers. The composer himself is seen alone in his room, swigging wine and finishing a musical composition; as he writes 'finis' at the bottom he collapses, dead. His daughters find him and grief descends on the house as the family realise the implications of his demise. Lewis contacts the uncle of Tessa and Pauline and he travels to Austria from Cambridge, where is a don, with his daughter, Florence. Florence finds herself attracted to the handsome but rather feckless Lewis and he quickly proposes to her. Their announcement causes Tessa to faint and she cannot disguise her distress.

It is decided that Tessa and Pauline should be sent to boarding school in England, while Lewis and Florence settle in her Chiswick home. But the romance that blossomed in the beautiful alpine surroundings is stifled by the demands of London society and Florence's ambitions for her talented husband. Toni has married Ike and they have also settled in London. Meanwhile, Tessa is miserable at school and she and Pauline decide to run away, turning up at Florence's house on the night of her first musical evening, aimed at promoting her husband to her cultured friends. Annoyed by the arrival of her cousins, Florence reluctantly allows them to stay but Lewis behaves dreadfully, humiliating her in front of the gathering.

Tessa's presence in the house causes tension, as the attraction between her and Lewis becomes apparent. His cruelty to Florence contrasts with his devotion to her cousin, driving a wedge between the couple. The date of Lewis's first major performance at the Queen's Hall is approaching and he determines to leave her after the concert; impulsively, Tessa agrees to come with him. Florence has a row with Tessa and forbids her to attend the concert, locking her in her room. But Tessa climbs out of the window with her possessions in a bundle.

The concert is a huge success. Afterwards, snubbing the guests gathered in his dressing room and again humiliating Florence, Lewis heads to the station and he and Tessa begin their journey to Brussels. While boarding the boat, Tessa faints and her condition worsens when they arrive at a dingy Belgian boarding house. Guilt-ridden, Lewis starts to write to Tessa's uncle, to throw himself on his mercy and try and salvage Tessa's reputation. But it is too late and Tessa perishes from a weak heart.