The case of little William Tyrrell is one of Australia's most baffling and heartbreaking mysteries. He was playing hide-and-seek with his four-year-old sister in the garden of his grandmother's house in Kendall on the NSW mid-north coast at around 10:30 am on September 12, 2014 when he disappeared, seemingly into thin air. It's a tragic story that has gripped Australia's imagination and the photo of the little boy playfully roaring like a tiger, wearing his Spiderman suit, has become an iconic image. Police have cleared his family of any involvement and believe it's likely he was abducted by an opportunistic stranger. His foster parents, birth parents and grandparents are shattered. Who would take this vivacious, funny, innocent three-year-old boy? How can a child simply disappear? This is the awful and unsettling story of a disappearance, a family tragedy, a driven detective, and a long and immensely frustrating police case. It is also the story of Australia's foster care system, exploring how and why a young child like William ends up in the foster care system.