Living on her family's idyllic lakeside estate in Cornwall, England, Alice Edevane is a bright, inquisitive, innocent, and precociously talented sixteen-year-old who loves to write stories. But the mysteries she pens are no match for the one her family is about to endure. One midsummer's eve, after a beautiful party drawing hundreds of guests to the estate has ended, the Edevanes discover that their youngest child, eleven-month-old Theo, has vanished without a trace. What follows is a tragedy that tears the family apart in ways they never imagined. Decades later, Alice is living in London, having enjoyed a long successful career as an author. Theo's case has never been solved, though Alice still harbors a suspicion as to the culprit. Miles away, Sadie Sparrow, a young detective in the London police force, is staying at her grandfather's house in Cornwall. While out walking one day, she stumbles upon the old estate -- now crumbling and covered with vines, clearly abandoned long ago. Her curiosity is sparked, setting off a series of events that will bring her and Alice together and reveal shocking truths about a past long gone, yet more present than ever.