The Diamond Master

An unexplained, carefully wrapped package containing a flawless large diamond arrives at the office of a jewelry-house president, triggering a chain of similar deliveries and mysteries. Company officers, an astute associate, a detective, and other participants probe the gems' origins, weighing smuggling, customs records, and unlikely domestic production, while following clues that include carrier pigeons and cryptic notes. The inquiry exposes mysterious figures and mounting dangers; partial truths are revealed, a key character named Mr. Czenki offers an important explanation, and events build toward a startling mechanical contrivance known as the great cube.