Pearl follows Cecily, the secluded and controlling mother of Margaret, a young woman with a sickness caused by her strange ability to cough up pearls. When a doctor from the city finds out about them their life in their isolated house by the sea changes forever. As the modern world invades their lonely environment they can no longer remain in their fairy-tale existence. While Margaret deteriorates, their world crumbles, and Cecily is forced to make a difficult decision: whether to save Margaret or let her die...