The story begins with Dr. Thorndyke, a brilliant forensic investigator, recounting a peculiar case to his friend and colleague. An ancient casket has been discovered in a hidden chamber beneath a country estate. The casket, ornately crafted and sealed, contains mysterious documents written in an unknown script. The circumstances of its discovery are baffling—no one knows how it got there, and the antiquarian who first found it has vanished without a trace. Thorndyke is drawn into the mystery, intrigued by the blend of archaeology, cryptography, and potential foul play. The chapter sets the stage for a cerebral investigation, hinting at secrets buried in history and the possibility of danger lurking behind scholarly curiosity.