The story follows Evelyn Preston, a young woman who returns to her locked-up family house and becomes entangled in a complex murder mystery involving an unidentified corpse, cryptic clues, and missing diagrams. As investigators and acquaintances pursue contradictory leads—telegrams, forged handwriting, bribery, and a concealed chess problem used as a clue—Evelyn navigates social circles and layered deceptions while personal relationships complicate the inquiry. Gradually, evidence is pieced together, identities are established, and the true conspirators are exposed through careful deductions that resolve the tangled sequence of events.