When wildlife ranger Johnny Hayward discovers a terrified young girl hiding in the grasses, he joins the tight-knit staff in trying to solve the mystery of how the girl, Maeve, came to their land. But when the police arrive, she tells them that Johnny is her father. He goes along with the lie, a split-second decision that entangles them both in a lifelong cover-up. Decades later, Maeve's daughter, Ava, grows up believing that same lie. Ava's love for the Refuge, where she lives in the staff cabins with her mother and is training to be a tour ranger, prevents her from dwelling on the fact that her mother never leaves the grounds - and won't explain why. But after starting to date a local boy, Ava begins to question her sheltered upbringing, shocked to discover that life outside their fences is not the nightmare her mother always taught her to fear. She is obsessed with answering one question: What is her mother so afraid of? Angry that her mother and Johnny won't give her answers, Ava follows a string of clues to investigate the disturbing events that led to Maeve's arrival all those years ago, unearthing secrets that some will do anything to keep buried.