A dying man drags his oxygen machine into the office of Éric Besson, a lawyer in Paris's thirteenth arrondissement. For decades, the old man has been helping a cadre of dirty cops launder stolen money and has been keeping meticulous investment records to prove it. The dilapidated notebook he hands over to Besson contains his full confession—he's waited fifty years to make it, and now he can't wait another day. He is adamant that Besson get the notebook into the hands of La Proc, Paris's chief prosecuting attorney, so the corruption can finally be brought to light. But en route to la Proc, Besson's courier—his assistant and nephew—is murdered, and the notebook disappears.
Grief-stricken, Éric Besson tries to hire private investigator Aimée Leduc to find the notebook, but she is reluctant to get involved. Her father was a cop and was murdered by the same dirty syndicate the notebook implicates. She's not sure which she's more afraid of, the dangerous men who would kill for the notebook or the possibility that her father's name might appear in its pages. Ultimately that's the reason she must take the case, which leads her across the Left Bank, from the Cambodian enclave of Khmer Rouge refugees to the ancient royal tapestry factories to the modern art galleries, in a race against the clock to thwart these men who will stop at nothing to protect their criminal enterprise—even threatening Aimée's infant daughter.