This is a 1972 story by Finnish writer Tove Jansson, her independent work, unrelated to the Moomin cycle. The book was translated into Russian in the 1980s and has been repeatedly reprinted ever since.
Sommarboken is a small work, wonderful beyond words. Her main character is the girl Sophia, who recently lost her mother, spending the summer with her father and her grandmother on a tiny virgin island in the Gulf of Finland.
Close, as can be assumed, will play the grandmother. The father will be played by Norwegian actor Anderson Danielsen Lie (“Paris. City of Zombie”). Directed and produced by Charlie McDowell (“Legion,” “Tales from the Loop”), son of Malcolm McDowell.
Filming will begin in Finland in the summer. The release date has not yet been determined.