The Homemade God by Rachel Joyce

Goose and his three sisters gather at their father's home by Lake Orta in Piedmont, Italy. Their father, a famous artist, has recently remarried a much younger woman and decamped to Italy to finish his masterpiece; now he is dead. There is no sign of his new wife and no sign of a painting. Always close, all that the siblings come to understand, about themselves, their father and their new stepmother, Bella-Mae, will drive them apart before they can come to any kind of understanding of what their father's legacy truly is.