Dead Man’s Folly by Agatha Christie

At a country estate, a seemingly harmless “murder game” is organized for entertainment, where participants stage a mock crime for fun. But the illusion of play turns dark when a real murder occurs during the event. Hercule Poirot is called in to investigate a case where fiction and reality dangerously overlap. As he examines the estate, its guests, and their hidden motives, he discovers that the victim may have been chosen long before the game even began.