In Agatha Christie’s novel The ABC Murders, what do the killer’s clues form?

In Agatha Christie’s novel The ABC Murders, the killer’s clues form the alphabet.

The 1936 mystery follows Hercule Poirot as he investigates murders apparently arranged according to alphabetical order. The crimes begin with a victim whose surname starts with A in a place beginning with A, followed by B and then C. An ABC railway guide is left beside each body.

The pattern makes the case appear methodical and highly distinctive, but Christie uses it to explore misdirection and the danger of accepting an obvious theory. The title is often printed as The A.B.C. Murders or The ABC Murders. It should not be confused with Christie’s novel And Then There Were None, which has a different structure and cast.