September 11, 1935 (Doncaster murder)

September 11, 1935, is both the announced date of the next murder in the anonymous letters and the date on which the Doncaster episode unfolds. Its importance lies not only in the warning’s promise of a further crime, but in the pressure the prediction exerts on Alexander Bonaparte Cust: the date seems to confirm his increasingly fearful sense that he is involved, while Hercule Poirot later explains how that impression was deliberately engineered.

The warning and its public reach

The fourth letter arrives after the earlier murders have failed to satisfy its writer. Addressing Poirot and the police with taunts, it names Doncaster and September 11 as the setting and date of the next incident. The message turns the sequence of crimes into a timetable, inviting the authorities and the public to anticipate what comes next. Its apparent precision is part of the threat’s force: a future crime is presented as something already scheduled.

The warning’s information travels beyond the investigators. Mrs Marbury, Cust’s landlady, has read the newspaper headlines and tells him that Doncaster is where the next murder is supposed to happen, and that it is due the following day. She imagines that anyone in Doncaster whose name begins with D would be wise to leave. Her reaction shows how the letter’s alphabetical pattern has become public knowledge, while also revealing the fear and speculation it creates among people outside the investigation.

Cust under the pressure of the date

Cust says nothing when Mrs Marbury names Doncaster, but she notices that he looks unwell and urges him not to travel. He insists that he must go: he has always been punctual in his engagements, he says, and people must be able to trust someone who has undertaken a task. His answer gives the journey an ordinary professional explanation even as, in context, it sounds ominously like a commitment to the predicted crime.

The date weighs on Cust because the previous murders have already made him feel implicated. As Poirot later reconstructs his state of mind, Cust had been present at or near the scenes of the Andover and Bexhill crimes, and the Churston murder appeared to continue the same pattern. His epilepsy could involve gaps in memory, and Poirot describes him as nervous and highly suggestible. When an order sends him to Doncaster just as the letter identifies it as the next location, Cust feels as though events have become fate. He loses his nerve and suspects that his landlady is watching him, helping explain why the date becomes a personal crisis rather than merely a clue in the investigation.

Doncaster and the question of responsibility

The chapter marking the date begins with Doncaster, and the narrator recalls that September 11 as a day he expects to remember for the rest of his life. The emphasis makes the date a hinge between the advance warning and the consequences that follow: the letter’s prediction has become an event around which the investigation, public attention, and Cust’s fear converge.

Cust’s condition complicates the question of what he may have done and what he can remember. Dr Thompson confirms that Cust is epileptic and discusses the possibility that a person in a somnambulistic state might perform an action without awareness. He also says that, in the general view he describes, such an action must not be contrary to the person’s waking will. Thompson himself rejects the explanation for Cust’s case, arguing that the letters demonstrate premeditation and careful planning. The medical discussion therefore opens a question about memory and responsibility without settling it in Cust’s favor.

The date as part of the frame-up

Poirot’s account ultimately recasts the apparent pattern. The crimes near Andover, Bexhill, and Churston made Cust believe that his presence at each scene could mean he had committed them during lapses of memory. The Doncaster order intensifies that suspicion by appearing to align his next journey with the warning. But Poirot explains that the alphabetical sequence and the letter’s prediction served the false A B C’s purpose: they made Cust look like the author of a planned series and turned coincidence and manipulation into apparent proof.

Thus September 11 functions simultaneously as a public deadline, a source of fear for Cust, and a component of the deception aimed at him. The date’s apparent certainty encourages observers to read the murders as a single, orderly pattern; Poirot’s explanation shows that the pattern itself was constructed to conceal the real design and direct suspicion toward an unwitting scapegoat.