New York, 1942. The composer Béla Bartók, gravely ill and heartsick with nostalgia for his native Hungary, sits in his apartment listening to a recording of an old folk tune. His plight is nothing new, as much of his life had been spent fighting indifference if not outright hostility. In 1919 his ballet, The Miraculous Mandarin had been banned on moral grounds across Europe and was never performed in his lifetime.

The second scene of the ballet involves a prostitute under orders to attract new clients. She looks out of her window at the teeming street below. She sees a man and beckons. He comes up to her room and they face each other. He walks behind her and runs his hands over her shoulders. She looks up at him longingly. Hands caress skin and intertwine.

But as their lips are about to meet, the client is grabbed from behind by a gloved hand. Two other men proceed to beat and rob him, to the prostitute's delight. He breaks free, pulls a knife on them and runs out of the building. The two men give chase, which ends when the client is finally forced into a dead end. As he is beaten into a bloody pulp, Hungary erupts into revolution, the ballet's musical violence mirroring real-life events.

As an ardent nationalist in the early 1900s, Bartók had urged his fellow Hungarians to shun the phony gypsy image of their country as promoted by popular operettas like The Merry Widow. Genuine Hungarian folk music was largely ignored, and Bartók spent his life championing it, visiting the remote countryside, recording old folk tunes on wax cylinders and transcribing and analysing thousands of melodies. In doing so, he discovered an ancient but authentic national music whose sounds gradually permeated his own work.

A passionate naturalist, Bartók also collected insects, and made many nocturnal trips whose evocative atmosphere and unexpected discoveries also fed directly into his music. But he wasn't only influenced by Hungary - on a trip to Africa he recorded of Arab songs which inspired his Dance Suite.

An intensely shy, private man, Bartók shunned the limelight at every opportunity. Duke Bluebeard's Castle, his only opera, is explicitly about this, with Bluebeard trying to avoid exposing his innermost secrets, which are gradually teased out of him by his new wife Judith's insatiable curiosity. She persuades him to reveal the contents of a series of rooms, the final one containing her predecessors, whom she feels compelled to join. Bluebeard shuts the door, having sacrificed his marriage for his privacy.

Bartók, by contrast, had to sacrifice his privacy for his music. Unable to earn anything from his compositions, he fell back on his phenomenal pianistic skills and became an internationally renowned performer, but he felt this trapped him in unnatural, alienating routines. He continued to compose, including many works later universally acclaimed as major masterpieces, but at the time they were considered monstrously modernist. While being well aware of his music's value, he hated performing it to unsympathetic audiences, and became even more withdrawn as a result.

He was eventually driven into exile by the rise of Nazi Germany. Despite needing the money, he refused to allow his music to be performed in Germany and Italy, severing links with his German publishers after refusing to fill in a form investigating his racial origins. Hungary had a pro-Nazi government, to Bartók's disgust, though his mother's ill-health persuaded him to stay, even when the Nazis took over. After her death in 1940, he left for America.

In New York, he was overwhelmed by homesickness, and found life terrifyingly harsh and aggressive, especially in the labyrinthine subway tunnels that he had to travel daily. Every waking moment was invaded by sounds from outside. He was totally unable to compose a note for three years, surviving thanks to a job at Columbia University cataloguing folk music.

Finally, the conductor Koussevitzky commissioned a Concerto for Orchestra, more explicitly based on Hungarian folk music than anything he had written for two decades. It was the first real success of his career, but he was terminally ill with leukaemia, dying in September 1945 in Manhattan.