Ruthless executive Christine Rivière (Dame Kristin Scott Thomas) brings on Isabelle Guérin (Ludivine Sagnier) as her assistant, and she takes delight in toying with the young woman's innocence. But when the protégé's ideas become tempting enough for Christine to pass on as her own, she underestimates Isabelle's ambition and cunning - and the ground is set for all-out war.