I'm a big fan of Rose Tremain. I don't often re-read books, but I've read the The Way Home, about an economic migrant to Britain from Eastern Europe, several times: it's touching and funny and sad and warm, with complex, richly realised characters. Music and Silence - which I've also re-read and, thinking about it, may read again - is set in the 17th century Danish court - very different, and quite mesmerising.
Sonata: a type of composition in three sections (exposition, development, and recapitulation) in which two themes or subjects are explored according to set key relationships. It forms the basis for much classical music, including the sonata, symphony, and concerto. (Google)
The two subjects are two boys, Anton and Gustav, with Gustav being the point-of-view character. They live in a Swiss town where nothing much happens. Gustav's circumstances are materially and also emotionally poor; his mother seems bitter and cold, and unable to really love him. His life is enriched when he makes friends with a new boy, a musical prodigy, whose parents are loving and warm and take Gustav into their hearts.
The second section goes back in time to explore the story of Gustav's parents (his father died during the war - in which, of course, Switzerland did not take part - when he was very small). Then the third section moves forward in time, to explain what becomes of Anton and Gustav in middle age.
As in all Rose Tremain's books, no matter how diverse their settings, the characters in all their complexity are the focus. And not just the main ones: Lotte, beautiful in her youth, still hungry for life, passion and fashion in her old age, is a wonderful creation. Even bit-part players, like Lunardi the chef, is completely three-dimensional; though he says little, he's very real. She explores and highlights relationships: weakness, selfishness, the accommodations that people make, the deceptions they learn to live with - but also the strength of love, the kindness and generosity to be found in unexpected places.
I knew nothing about life in Switzerland during the war, and it was interesting to discover how, despite being neutral, it was still affected. But really, what grips is the story of these two lives, and how they touch and are touched by those of others. It's a satisfying, thought-provoking and moving novel, and you really couldn't ask for much more, could you?