After the death of his grandmother Emma, Robin Hunzinger and his mother Claudie found a carefully preserved collection of letters which Emma received from a girl called Marcelle. Marcelle and Emma met in the mid-1920s. Secretly, love blossomed between the two teenage girls, but after two years they parted ways. Marcelle developed tuberculosis and was admitted to a sanatorium, where she wrote many letters to Emma, letters that still burn with great evocative power. At the sanatorium, rebellious Marcelle, nicknamed ‘Ultraviolette’, led a group of three young women who were also sick. The film, told through Marcelle’s eloquent letters, combines archive footage, avant-garde films, and music to create a sensuous, poetic atmosphere of absolute love, a daring young woman ahead of her time and a group of kindred spirits which break the barrier of time.