Fair warning: Dumb Witness is best read after The Mysterious Affair at Styles; The Murder of Roger Ackroyd; The Mystery of the Blue Train; and Death in the Clouds—since the identity of the criminal in each is revealed in this novel.

• Glasgow Herald: ‘One of Poirot’s most brilliant achievements.’

18. Death on the Nile (1937)

Among the best-loved of Agatha Christie’s novels, Death on the Nile finds Hercule Poirot again trying to enjoy a vacation—this time aboard the S.S. Karnak, steaming between the First and Second Cataracts of the Nile, with stops at sites of archaeological significance. But Poirot (who, after all, had attempted to retire years before) seems to be perennially unlucky in his choice of holidays. Newlywed Linnet Ridgeway is, in the course of the journey, shot dead in the head, and Poirot has before him a boatload of suspects—and a useful sidekick in Colonel Race of the British Secret Service.

Of note: The producers of Murder on the Orient Express released a film version, also well received (though not by Mrs Christie, who had passed away two years prior), of Death on the Nile (1978), this time casting Peter Ustinov as Poirot.

• Daily Mail (of the novel): ‘Flawless.’

19. Appointment with Death (1938)

‘“I’m so sorry,” she said…“Your mother is dead, Mr Boynton.” And curiously, as though from a great distance, she watched the faces of five people to whom that announcement meant freedom…’

We have returned to the Middle East with Hercule Poirot, on our most colourful tour yet: to the Dome of the Rock, the Judean desert, the Dead Sea, and to Petra, ‘the rose-red city,’ that ancient place of heart-stopping beauty—but also of heart-stopping horror, for here sits the corpse of old Mrs Boynton, monstrous matriarch, loathed by one and all. A tiny puncture mark on her wrist is the only sign of the fatal injection that killed her. With only twenty-four hours available to solve the mystery, Hercule Poirot recalls a chance remark he’d overheard back in Jerusalem: ‘You see, don’t you, that she’s got to be killed?’

• The Observer: ‘Twice as brilliant as Death on the Nile, which was entirely brilliant.’

20. Hercule Poirot’s Christmas (1938)

This novel was the author’s gift to her brother-in-law, who had complained that her stories were, for him, ‘too academic.’ What he desired was a ‘good violent murder with lots of blood.’ From the epigraph—a quotation from Macbeth—to its startling end, Agatha delivered a gift made to order.

It is Christmas Eve. The Lee family reunion, never a lively affair, is interrupted by a deafening crash and a high-pitched scream. The tyrannical head of the Lee family, Simeon, lies dead in a pool of blood, his throat slashed. Hercule Poirot is spending the holidays with his friend Colonel Johnson, the chief constable of the local village. At the Lee house he finds an atmosphere not of mourning but of mutual suspicion. Christmas with family—survive it this year with Hercule Poirot.

Fair warning: In an exchange between Poirot and Colonel Johnson, the solution of Three-Act Tragedy is revealed.