S05E02 - The Under Dog

Sir Reuben Astwell was murdered ten days previously at his country house, Mon Repos, when he was violently hit on the back of the head with a club and his nephew Charles Leverson has been arrested. Sir Reuben's wife, Lady Astwell, is convinced that the true criminal is the late man's secretary, Owen Trefusis, although she doesn't have a shred of evidence to back up this claim, relying instead of her much-vaunted and self-proclaimed 'intuition'. She sends her young companion, Lily Margrave, to Poirot to employ him on the case and Poirot accepts, partly because he senses that Lily does not want Poirot to investigate the matter and that she has something to hide.