Mika (Isabelle Huppert) is the head of a Swiss chocolate company and insists on dispensing a surprisingly potent blend of hot chocolate and sedatives to her family. Married for the second time to her concert-pianist husband Andre, the two live with their son Guillaume, who clearly shares none of his father's musical talent. Into their lives steps a young woman born on the same day as Guillaume and, as we learn, was almost switched at birth with him. Does her prolific talent at the piano hint at a deeper connection? And will there be enough chocolate to go around?