Five days before D-Day, the day of the last voyage of the Order of Sirius, a sect nestled in the Vaudoise Alps, Switzerland. Five days during which a community of 48 people, women, men, children, fed with esotericism and guided by a narcissistic guru, will test their faith and be deprived of their identity. Five days in which every gesture will be the last. Sirius is inspired by the massacre of the Order of the Solar Temple in 1994 in western Switzerland.
Recently separated, top neurologist Dr. Valérie Rossier moves back to her ancestral home with her son Lucas, and takes a position in an exclusive clinic run by her former teacher, Professor Wassermann. As she settles into her new life, strange occurrences conspire to reveal her true heritage, as well as her family's tragic history.