Gustav Perle, son of a dead policeman and a bitter mother whom he loves despite her disaffection for him, is merely 5 as this story opens, but already he has "mastered" himself. He is Swiss, and that's what the Swiss do, he's told. Switzerland, where World War II failed to trespass, is like a coconut - the shell fibrous and difficult to penetrate, protecting the nourishment inside.
So, as a Swiss national, he must hold himself together, be courageous, and stay separate and strong. Only then will he have "the right kind of life". The right kind of life, then, appears to be in a freezing, second-floor flat on Unter der Egg, a flat with no table, merely a hinged shelf. The right kind of life gives him but one toy, a tin train with passengers' faces painted on in expressions of blank surprise as they travel up and back along the window sill of the cold flat. The passengers have names; they are his friends, in a way.
At 6, Gustav Perle meets a new arrival at kindergarten, a fearful and emotional boy called Anton Swiebel, who stands and weeps after his mother so that his face becomes a "hectic pink". Anton is a Jewish boy, the only son of kind, wealthy parents, who already plays basic classical music on the Swiebel's grand piano and is headed, he hopes, for a career on the concert stage.
Anton and his parents feel for Gustav Perle and his compromised life and want to help him; Gustav Perle sees it as his duty to help Anton "master" himself and during their lifetimes they come to understand each other's inner people. Theirs is an achingly moving friendship.
This scenario is the springboard for Rose Tremain's 13th novel. Her reputation for "fierce, astringent and profoundly tender" writing is fully realised here. She knows and loves her characters, and carries them tenderly through their journey, always with a hugely strong entourage of support characters.