This is book number 1946 in the Hercule Poirot Mysteries (Audio) series.
Agatha Christie's classic, The Hollow, finds Poirot entangled in a nasty web of family secrets when he comes across a fresh murder at an English country manor.
A far-from-warm welcome greets Hercule Poirot as he arrives for lunch at Lucy Angkatell's country house. A man lies dying by the swimming pool, his blood dripping into the water. His wife stands over him, holding a revolver.
As Poirot investigates, he begins to realize that beneath the respectable surface lies a tangle of family secrets and everyone becomes a suspect.