Five Little Pigs by Agatha Christie

""Five Little Pigs" by Agatha Christie is not part of a series. It's a standalone mystery novel featuring the famous detective Hercule Poirot. In the story, Poirot is approached by a woman named Carla Lemarchant, who asks him to investigate a murder that occurred 16 years earlier. Carla believes her mother was wrongly accused of poisoning her father, and she wants Poirot to uncover the truth. Poirot delves into the past, interviewing witnesses and examining the evidence, in an attempt to solve the long-cold case. The novel is a classic example of Christie's intricate and compelling mystery writing.