June 1933, and sixteen-year-old Alice Edevane is preparing for her family's Midsummer Eve party at their country home, Loeanneth. But by the time midnight strikes, and fireworks light up the night sky, the Edevane family will have suffered a loss so great they leave Loeanneth forever.
Seventy years later, after a particularly troubling case, Detective Sadie Sparrow retreats to her beloved grandfather's cottage in Cornwall. Once there, she stumbles upon a long-abandoned house, and learns the story of a baby boy who disappeared without a trace.
Meanwhile, in her elegant Hampstead house, the formidable Alice Edevane now leads a life as neatly plotted as the bestselling detective novels she writes. Until a young police detective starts asking questions about her family's past, seeking to resurrect the complex tangle of secrets Alice has spent her life trying to escape.
With a mystery that's become deeply personal to Sadie, and a novelist who is intent on hiding the past, can the secrets of that night ever be solved?