The novel is an example of a "country house mystery" and was the first of her novels in four years to feature Christie's Belgian detective Hercule Poirot—one of the longest gaps in the entire series. Christie, who often admitted that she did not like Poirot (a fact parodied by her recurring novelist character Ariadne Oliver), particularly disliked his appearance in this novel. His late arrival, jarring, given the established atmosphere, led Christie to claim in her "" that she ruined the novel by the introduction of Poirot.