At Bertram's Hotel
Agatha Christie
 Jane Marple, the elderly amateur sleuth, takes a holiday at Bertram's hotel in London, to re-live her happy memories of staying there during her youth. The hotel is famous for fully preserving its Edwardian atmosphere even into the 1960s, from the proper staff to the elderly guests who frequent the tearoom. Miss Marple first sees Lady Selina Hazy, a childhood friend. Lady Hazy says she often thinks she recognizes people in the hotel but they turn out to be strangers. Miss Marple is intrigued by the other guests in the tearoom, especially a famous adventuress, Bess Sedgwick; a young woman, Elvira Blake, and her guardian Colonel Luscombe; and a forgetful clergyman, Canon Pennyfather. Elvira's late father left her a lot of money, but it's all held in trust until she, not yet 20, turns 21. Her mother, Bess Sedgwick, had abandoned her as a toddler to become a famous star and adventurer, and has not kept in touch. Elvira suddenly starts asking her guardians who would inherit her money if she dies, and hints that she may be planning marriage. She also says somebody had tried to poison her during her school days in Italy. She secretly flies to Ireland for 24 hours, telling her best friend only that she has to find out something that's of terrible importance. Canon Pennyfather is supposed to fly to Switzerland the same day, also for 24 hours, to attend a religious conference in Lucerne. But he's so forgetful he doesn't arrive at the airport until the following evening, by which time the conference is over. He returns to the hotel around midnight, and upon entering his room, sees something very surprising and is immediately knocked on the head. He wakes up four days later in a house several hours from London but near the location where the Irish Mail train was robbed three days earlier. A family had found him on the side of the road and taken him in. He remembers nothing since taking the taxi to the airport, yet some witnesses at the train robbery say they saw somebody who looked like him at the scene. Miss Marple also saw him leaving his hotel room at 3 am, three hours after he was knocked on the head, and a few hours before the robbery. It turns out that Lady Sedgwick had hidden herself from Elvira because she did not consider herself a suitable mother, given her lifestyle. Sedgwick and Elvira are lovers of the same man, the racing-car driver Ladislaus Malinowski. However, both women claim that Elvira doesn't know him. But Miss Marple knows that she does, because she has seen Elvira and Malinowski together at a restaurant. She thinks Malinowski is an unsuitable man for Elvira, and wishes she could save her from getting involved with him. Meanwhile, a car similar to Malinowski's has been seen at the train robbery and at several other train robberies; it is similar but not identical: the licence plates were off by one digit. Miss Marple overhears Bess Sedgwick talking with the hotel commissionaire, Micky Gorman. It turns out they had earlier been married in Ireland. At the time, Gorman had told her the wedding was just a game and not a legal marriage. But in fact it was a real marriage, and so her four subsequent marriages were unwittingly bigamous. Elvira also overhears this, and worries it might invalidate her inheritance because she is the daughter of one of Sedgwick's later husbands. She had travelled to Ireland to verify the marriage, but we don't know whether she flew back to England or took a train, perhaps the Irish Mail train, so she could have been a witness or perpetrator in the robbery. When Elvira comes to the hotel one foggy night, two shots are fired, and Elvira is found next to dead Commissionaire Gorman. Elvira claims he has been shot dead after he had run in front of her to shield her due to the first shot. The gun is Malinowski's. Police Chief Inspector "Father" Davy, along with Inspector Campbell, has been involved in the mystery since Pennyfather's disappearance. He interviews everybody in the hotel, and quickly realizes that Miss Marple notices things — things in human nature that provide important clues. After Pennyfather is found, the three of them try an experiment. Miss Marple and Pennyfather re-enact their actions from when she saw him in the hallway (although he doesn't remember it). She realizes it wasn't him she saw: the walk was different. Pennyfather then remembers what surprised him when he entered his room: he saw himself sitting on a chair, just before he was knocked on the head. His doppelgänger, with his confederates, left the hotel (when Miss Marple saw him), drove the unconscious Pennyfather to the mail train, made himself visible during the robbery so that people would mistake him for Pennyfather, and then left Pennyfather on the side of the road. Miss Marple tells Inspector Davy that she was disappointed to find out that much of the hotel's Edwardian atmosphere is false. Some of the guests are genuine, but others are actors pretending to be other people. So Lady Hazy wasn't wrong after all; the people she mistakenly recognized were actors pretending to be people she knew. Why a hotel would have so many actors is baffling, until the sleuths realize that the hotel is the center of a criminal ring. The actors pose as other people during robberies in order to make it look like their namesakes were at places they weren't. "Father" Davy and Miss Marple confront Bess Sedgwick as the orchestrator of these robberies, along with the hotel's owners and staff. Sedgwick confesses, and also admits to killing Gorman. She then drives away recklessly and commits suicide, although her racing may let it look like an accident. However, Miss Marple has already concluded that Elvira herself shot Gorman, and that her mother falsely confessed to the shooting in order to save her daughter. Elvira had fallen madly in love with Ladislaus Malinowski and knew that he was primarily interested in her money, but was concerned that if Michael Gorman revealed his marriage to Bess Sedgwick it would endanger her father's legacy.