The Roussier family lives in a fragile equilibrium around the younger sister, Bertille, who suffers from a severe disability with an unclear diagnosis. Her parents, Madeleine and Gilles, and her sister Marion, each of them tries their best to deal with the doubts and needs surrounding this extraordinary child who could die at any moment. What does the future hold for this couple, and for Marion whose responsibilities made her grow up too fast? When a new diagnosis is unveiled, horizons open up…