The narrative begins at an English country estate centered on a newly wealthy owner and his observant butler, where guests and household rhythms are interrupted by personal tensions and a budding romance between a returning soldier and the estate's young woman. A series of discoveries—mysterious letters, coded papers, a man with a yellow face, and a silent shot—pull household members into an investigation that reveals hidden identities, deceptive appearances, and a perplexing riddle. As clues accumulate and suspects are confronted, secrets culminate in violence and a final reckoning that resolves the central mystery.