Agatha Christie - Dumb Witness (BBC Dramatization)

Hercule Poirot receives a letter from a rich, elderly spinster, Miss Emily Arundell. She is clearly in great distress, but doesn't say why. Poirot persuades Captain Hastings that they must visit the lady with all haste. On arrival, they discover that she has died of natural causes. But Bob, Miss Arundell's wire-haired terrier, knows better. And so does Poirot. John Moffatt stars as Hercule Poirot, with Simon Williams as Captain Hastings.