Peril at End House by Agatha Christie

"Peril at End House" by Agatha Christie is not part of a series but features her famous detective, Hercule Poirot. The story is set at a seaside resort in Cornwall, where Poirot and his friend, Captain Hastings, encounter a young woman named Nick Buckley. Nick believes she has narrowly escaped several accidents and suspects foul play. Poirot takes an interest in her case and begins to investigate the series of incidents. The novel is a classic Agatha Christie mystery, filled with twists, clues, and a clever resolution.