It is an incredible novel.
In 1910, a baby is born, and dies at birth. In 1910, the same baby is born, and lives through her first moments. In fact, every time Ursula Todd dies, she is reborn, with some vague sense of her previous lives hanging over her. So we follow Ursula through the First and Second World Wars, through the first half of the twentieth century, somehow both stuck to history and outside of it, because she can change her own. With her half memories, she manages to undo her mistakes, and avoid the mistakes of others towards her. We sit with her as she dies death after death, and lives life after life after life.