Bobby rejects a job offer from Buenos Aires. In the meantime he drinks from a poisoned beer bottle. Bobby discovers that Amelia Cayman is an imposter. He figures that the stranger at the scene of the crime must have switched the photo in the dead man's wallet. Bobbie and his friend Frankie search for Bassington-French and find an address in Hampshire. There, they stage a car accident hoping that Frankie, injured, will be invited into the home. Inside, Frankie meets Roger's brother, Henryk, and sister in law Sylvia. Frankie shows the couple a newspaper clipping of the dead man. Sylvia says he resembles a man who was good friends with a big game hunter, Alan Carstairs, who killed himself after being diagnosed with terminal cancer.
Frankie meets Henry and Sylvia's neighbours, Dr. and Moira Nicholson, who run a sanitarium. Bobby investigates the sanitarium where he runs into the beautiful woman from the photo. Moira turns up at the local inn where Bobby is staying and says her husband is trying to kill her. Frankie asks Roger if he took the photo of the beautiful woman and he admits that he dead, wanting to avoid scandal for her. In the meantime, Henry is found dead in his home, an apparent suicide.
Frankie asks a solicitor about Savage's will and finds out that he was staying with Mr. and Mrs. Templeton when he first discovered he had cancer. One specialist, however, said he was perfectly fine. When he died, he left 700,000 pounds to the Templeton's. Bobby is kidnapped and Frankie is lured, along with Roger, to an isolated cottage. Badger Beadon arrives to find a drugged Moira in the cottage. When the police appear on the scene, Roger has vanished.
They trace the witnesses to the signing of John Savage's will. They are the former cook and gardener of Mr.and Mrs. Templeton. The parlourmaid, Gladys, however, was not asked to witness the singing of the will. In reality, it was not John Savage who signed the document but Roger Bassington-French. Gladys' last name is Evans, hence the dying man's question: "Why didn't they ask Evans?" Gladys is now the housekeeper at Bobby's home and the dying man was trying to find her.
Returning to Wales, they find Moira who claims she is being followed by Roger. Frankie, suspicious of Moira, spoils the latter's attempt to poison their coffee. It turns out Moira was really Mrs. Templeton and Roger's accomplice. Moira attempts to shoot Bobby and Frankie but is overpowered. Weeks later Frankie received a letter postmarked South America from Roger who admits that he murdered Carstairs and his brother Henry. Frankie and Bobby get engaged.
Why Didn't They Ask Evans?, published in 1933, courtesy http://www.agathachristie.com/stories/why-didnt-they-ask-evans