借镜杀人

描述：Marple is asked by her lawyer, Christian Gilbranson, to visit his step-mother, Carrie Louise Serrocold, an old friend of Miss Marple's, at her country estate. Carrie's husband, Lewis, confides to Miss Marple that he suspects someone is slowly poisoning his wife, and when Gilbranson visits the mansion, he is mysteriously murdered.