During a visit to the Braille Museum in Coupvray, Aurore Blin, a 21-year-old blind woman, is given a signet ring that belonged to her father, who died twelve years earlier in a strange accident. Despite her blindness, the young woman, intrigued, decides to continue the research her father was conducting at the time of his death. She then sets out to discover the story of her ancestor, Henri Blin. In 1825, Louis Braille entrusted Henri Blin, a teacher at the National Institute for Young Blind People, with the task of protecting the original matrix of his writing system, which was coveted for military purposes by the French and English secret services...