Shroud for a lady

Miss Julia Paxton has a mystery that only Gamadge could solve. The framed etching of Lady Audley had always hung in the hallway of the Ashbury mansion. Miss Paxton remembered it from her girlhood, and she was now a hale and hearty seventy-five. But never in all those years had she seen one word written on the portrait. In fact, none had been there — until after the visit last Sunday of Iris Vance, professional medium. Then the inscription, dated 1793, appeared. But how? Gamadge could tell the writing was genuine, he could even explain its presence without invoking the supernatural... but he couldn't stop Lady Audley's secret from leading to a most horrible murder.