The Tragedy at Marsdon Manor (S03E06)

Poirot is called to Marsdon by the proprietor of a local inn to investigate a murder. However, the innkeeper, an aspiring thriller novelist, reveals that the murder is merely a plot device from his manuscript. Just as Poirot feels disheartened, a genuine, eerie murder occurs at the nearby manor. The case takes a strange turn when a young wife insists her garden tree is possessed by a ghostly laughter, accompanied by hints of dark magic from East Africa. Poirot sets a clever trap to reveal the murderer, confident that the culprit is merely human.