The summer of 1976 was the hottest in living memory. Britain sweltered, trees and plants wilted, fire ripped through forests, and rivers ran dry. In London's Kew Gardens, a 10-year-old girl was parted from her friends and, dizzied by scorching heat, wandered lost into its secluded undergrowth. Forty years later, the detective's daughter Stella Darnell takes on a chilling new case. Along with Jack, a train driver, she will be drawn to the secret spaces of Kew, and to an unsolved murder that has lain dormant for decades.