Gyp, the daughter of ex-Major Charles Claire Winton, at the age of 23 marries Fiorsen, a Swedish violin virtuoso. Her mother, the wife of another man, has been Winton's mistress; she had died when Gyp was born. A highly sensitive child, Gyp has grown up in isolated surroundings with a kind, but very British, father.

As she gets older her father tries to introduce her into society. An attack of gout takes him to Wiesbaden for a cure and, as he never goes anywhere without her, she accompanies him. There she is mesmerised by Fiorsen and his playing. Intensely musical herself and inexperienced, she's flattered by the homage of the violinist although her father soon sees through him. She also sees he is talented but unstable, ignorant, vain, hypersensitive, with an air of romance – a typical virtuoso.

Gyp realises that she may well have made a mistake in marrying Fiorsen. The book follows what happens to her thereafter.