Northern France, 2016. Rama, a successful Parisian journalist and author, has travelled to the coastal town of Saint-Omer to document the trial of Laurence Coly, a well-educated young Senegalese Frenchwoman who is accused of abandoning her 15-month-old daughter on a beach at high tide. At work on a modern-day adaptation of Medea, Rama plans to incorporate Laurence's story into her new novel, but the case affects her in unexpected ways.