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The Big Four · Chapter

XI: A Chess Problem explained

Poirot and Hastings dine with Inspector Japp, who discusses the mysterious death of American chess champion Gilmour Wilson during a match against Dr.

What happens

Poirot and Hastings dine with Inspector Japp, who discusses the mysterious death of American chess champion Gilmour Wilson during a match against Dr. Savaronoff. Poirot deduces that Wilson was electrocuted via a rigged chess piece and table, orchestrated by the Big Four. He identifies the niece Sonia Daviloff as an agent and the servant Ivan as Number Four, leading to a chase.

Themes in this chapter

  • Global Criminal Conspiracy

    The Big Four orchestrate Wilson's murder as part of their criminal network, with Number Four and Sonia Daviloff as agents.

  • Intelligence and Deduction

    Poirot uses his 'little grey cells' to deduce the electrocution method and identify the culprits, contrasting with Japp's initial theories.

  • Deception and Disguise

    Number Four assumes multiple identities (Ivan, asylum attendant, etc.) and the murder is disguised as heart failure using a rigged chess set.

Characters to notice

  • Hercule Poirot

    Dines with Hastings and Japp; deduces the murder method involving an electrified chess piece and links it to the Big Four.

  • Captain Hastings

    Narrates the chapter; discusses the case with Poirot and retrieves a chess book for him.

  • Inspector Japp

    Joins Poirot and Hastings at dinner; shares details of Wilson's death and suspects poison meant for Savaronoff.

  • Gilmour Wilson

    American chess champion who dies suddenly during a match; victim of electrocution via a rigged chess piece.

  • Dr. Savaronoff

    Russian chess champion; opponent in the match; reluctant to play due to fear of the Big Four.

  • Number Four

    Identified as the servant Ivan; master of disguise and orchestrator of the murder plot.

Key passages

  • I’ve been up north—that’s why. How are things with you? Big Four still going strong—eh?

    Japp asks Poirot if the Big Four is still active.

    Japp's casual inquiry about the Big Four.

  • Wilson was sound as a bell—no trace of heart trouble. His death is quite inexplicable.

    Wilson had no known heart issues, making his sudden death suspicious.

    Japp explains the mystery to Poirot.

  • I don’t believe the poison was meant for Wilson—it was meant for the other man.

    Japp theorizes that Savaronoff was the intended target.

    Japp's initial theory about the murder.

  • Wilson was not poisoned, he was electrocuted. A thin metal rod passes up the middle of one of those chessmen.

    Poirot reveals that Wilson was killed by an electric current through a modified chess piece.

    Poirot's deduction of the murder method.

  • I strongly suspect that Ivan is none other than the famous Number Four.

    Poirot identifies the servant Ivan as the master criminal Number Four.

    Poirot's revelation about Ivan's true identity.

The Big Four — XI: A Chess Problem Explained