The young violinists and friends Marie Wendel and Kim Cheng both go to the final of the Queen Elisabeth Competition in Belgium. A false note and Marie's career comes to an end, while Kim takes off for solo successes. Disappointed, Marie vegetates in the memory of her older sister Clara, a pianist, who died in a car accident. With her, Marie formed Alter Duo, a fusional ensemble. It will take the flair of Max Kieffer, an agent, to relaunch Marie alongside Luigi Faena, a famous Italian pianist looking for a new career. Orion&Sirius will be their perfect duo until the voluntary disappearance of Luigi during a concert in Spoleto. With his unexplained absence, Marie's world crumbles. How will she be able to bounce back, rebuild herself? Marie sees only one solution: to follow in the footsteps of Luigi in the Italy of his youth. There, in Umbria, with the help of Francesco an old friend of Luigi’s, she will have to face what she did not want to see: osteoarthritis which slowed down Luigi's tempo a little more each day. Marie then wants to put away her violin and forget her Alter Duo absolute forever. Unless Kim takes over the score of their friendship to show him a new way of musical life.