A grieving mother (Emmanuelle Devos) decides to investigate the hit-and-run accident that killed her son after the police are unable to find any leads. When she tracks down those responsible -- a couple (Nathalie Baye and David Clavel) living in the French spa town of ?vian -- she insinuates herself into their lives as she plots her next move. Directed by Fr?d?ric Mermoud, Moka is based on a novel by Tatiana de Rosnay.