Having followed the brilliant virologist Régnier from Montreal to Marseille many years ago, Sadie now works as a researcher in a lab, spending most of her time among microscopic creatures who teach her about life as a parasite. By day, she pushes the limits of her understanding alongside Régnier, who taught her that to study viruses, she must think infectiously, allow herself to be contaminated by dangerous ideas. By night, Sadie loses herself in bars, music, drugs, sensuality. Until she gets a call from the past that lures her back across the Atlantic. When her estranged father tells her...