The novella is an expanded version of the short story The Second Gong which was first published in 1932.
(may contain spoilers - click on expand to read)
When Sir Gervase Chevenix-Gore writes to Hercule Poirot to unceremoniously summon him down to the Chevenix-Gore ancestral pile, Poirot is initially reluctant to go. However, there is something that intrigues him and so he catches the train that Sir Gervase wanted him to. On arrival, it is clear that no-one was expecting him, and, for the first time in memory, Sir Gervase himself, who is always punctual, is missing. Poirot and guests go to his study and find him there dead, having apparently shot himself. Poirot is not convinced, however, and soon starts to prove that Sir Gervase was murdered because of various improbable factors surrounding the death, including the position at which the bullet is believed to have struck a mirror and the many different moods that Chevenix-Gore exhibited during the day.
When Poirot first arrives at the Chevenix-Gore's house, he meets Chevenix's wife Vanda, an eccentric who believes she is a reincarnation of an Egyptian woman, his adopted daughter Ruth and her cousin Hugo, and Miss Lingard, a secretary helping Chevenix research a family history. It is revealed that before Poirot arrives, all the guests and family were dressing for dinner, and after they heard the dinner gong, a shot rang out. No one suspected that anything is wrong, believing that either a car had backfired or champagne was being served. And Chevenix-Gore not being the most popular of men, there are any number of suspects, including his own daughter and nephew. It is revealed that Hugo is engaged to Susan (another guest at the house) and Ruth has already married Lake (Chevenix-Gore's assistant) in secret.
In the end, Poirot assembles everyone in the study. He tells them that Chevenix intended to disinherit Ruth if she did not marry Hugo Trent. However, it was too late, as she was already married to Lake. Poirot says that Ruth killed Chevenix, but Ms Lingard confesses in the murder. She is the real mother of Ruth and she killed Chevenix in order to prevent him from disinheriting her.
The bullet which killed Chevenix hit the gong (as the door to the study was open), which made Susan think that she heard the first gong (dinner was usually served after the valet would strike the gong 2 times), and it was Ms Lingard who smashed the mirror and made the whole affair look like suicide. She blew a paper bag in order to fake a shot. Poirot claims to suspect Ruth because he suspected Ms Lingard would rescue her daughter and confess, and he had no evidence against Ms Lingard. After everyone leaves and Ms Lingard stays alone in the room, she asks Poirot not to tell Ruth that she is her real mother. Poirot agrees as Ms Lingard is terminally ill, and does not reveal anything to Ruth who wonders why Ms Lingard committed the murder.
- Hercule Poirot
- Gervase Chevenix-Gore of Hamborough Close
- Mr Satterthwaite
- Ruth Chevenix-Gore
- Miss Lingard
- Vanda Chevenix-Gore
- Captain John Lake
- Hugo Trent
- Susan Cardwell
- Godfrey Burrows
- Major Riddle
- Colonel Ned Bury
- Oswald Forbes
References to other stories
- Mr Satterthwaite tells Poirot that he enjoyed working with Poirot during the "Crow's Nest business" (Three Act Tragedy). He tells Poirot he had just met Lady Mary Lytton Gore a week ago.
Film, TV, or theatrical versions
Agatha Christie's Poirot
- 1937: Murder in the Mews and Other Stories, Collins Crime Club (London), 15 March 1937
- 1937: Dead Man's Mirror, Dodd Mead and Company (New York), 1937 (same collection as the Collins Crime Club edition above but minus The Incredible Theft)
- 1954: MacKill's Mystery Magazine, vol. 4 no. 1, Mar 1954.
- Cover illustration is about the story, with headings: "Dead Man's Mirror, A complete Mystery Novel by AGATHA CHRISTIE".
- 1954: Mackill's (US) Mystery Magazine, vol. 4 no. 1, May 1954.
- 1966: Ellery Queen's Mystery Magazine, vol. 47 no. 2, whole no. 267, Feb 1966, as "Hercule Poirot and the Broken Mirror".
- A text box on the cover announces "Complete Short Novel AGATHA CHRISTIE".