S03E10 - The Mystery of Hunter's Lodge

Poirot is ill in bed with influenza when he and Hastings receive a visit from a Mr Roger Havering, the second son of a Baronet who has been married to an actress for some years. Mr Havering stayed at his club in London the previous evening and the following morning receives a telegram from his wife telling him his Uncle, Harrington Pace, was murdered the previous evening and to come at once with a detective. As Poirot is indisposed, Hastings sets off with Havering for the scene of the crime – Derbyshire.
Mr Pace, an American by birth and the brother of Mr Havering's mother, owns an isolated hunting lodge on the Derbyshire moors. When Hastings and Havering arrive there they meet Inspector Japp as Scotland Yard has been called in on the case. As Havering goes off to answer questions, Hastings speaks with the housekeeper, Mrs Middleton, who tells him she showed a black-bearded man into the house the previous evening who wanted to see Mr Pace. She and Mrs Havering were outside the room that the two men were talking in when they heard a shot. The door to the room was locked but they found the window outside open and gaining entry found Mr Pace dead, shot by one of two pistols on display in the room and the used pistol now missing, together with the black-bearded man. Mrs Middleton sends Mrs Havering to see Hastings and she confirms the housekeeper's story.