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.
Yiya Murano poisoned her friends to cover up scams in 1970s Argentina and became a dark figure in popular culture. Freed in the 1990s, she reappeared as a pop icon. Today, her son Martín seeks to reveal her true face.