The Oracle at Delphi: A Parker Pyne Story (Parker Pyne Mysteries)

Previously published in the print anthology Parker Pine Investigates. Parker Pyne is traveling incognito under the name of Mr. Thompson. In Delphi, he learns that someone calling himself Parker Pyne is being consulted by Mrs. Peters, who refers to him as "the good gentleman." But who is this imposter, and what does he want with Mrs. Peters?