The Tragedy at Marsdon Manor (S03E06)

In his remote country house Jonathan Maltravers is recovering from an ulcer with the help of his much younger wife Susan. When one of the staff finds his body under an oak tree, Susan swears that a ghost who haunts the tree is responsible. Poirot and Hastings are staying at a nearby hotel working on another case. Called to Marsdon Manor, Poirot soon deduces that Maltravers did not die of natural or supernatural causes. (iTunes)