On a secluded island off the British coast, an elderly woman named Marianne collects butterflies and memories from her past. No longer able to catch butterflies herself, she enlists the help of a young woman named Tartelin who has peculiar birthmark on her cheek. Tartelin’s mother has recently passed, leaving her unmoored and eager for new beginnings on the island.   Marianne has spent most of her life on the island, her family having owned it for generations. She begins to tell her young assistant her family’s story – from the prosperous days when they harvested pearls and held banquets, to the harder times and her father’s desperate money-making schemes. But during WWII, the British government commandeered the island for nuclear testing and they were all forced to leave. Though, secret to everyone, Marianne stayed behind and experienced something she calls “the blast,” an event that changed everything for her. Now, the older woman is