Films about obsession usually start in the before, the halcyon days of family and friends and home. A little background that helps explain the protagonist’s turn once it’s all shattered. Not in Moka, the new film by Frédéric Mermoud and adapted from the eponymous novel by Tatiana de Rosnay. We enter this one at full tilt with Diane Kramer (Emmanuelle Devos), a woman already consumed.