Bol'shaia chetverka - Kristi Agata

This novel is not typical of Christie in its form. It is built not as a whole plot, but as a chain of novels, where each featured individual members of the mysterious and elusive "Big Four" - a secret organization seeking to seize world domination.

A haggard man in a stained suit breaks into Hercule Poirot's house. He's barely alive. A few drops of cognac make him feel. A person tries to explain something, but he has enough strength only to write a large number "4" on a piece of paper several times...