Agatha Christie - The Crooked House (Complete and unabridged, read by Hugh Fraser)

In the Three Gables estate of the Leonides family, someone has poisoned old Aristide. Suspicion falls on his very young wife, bound to inherit a fortune. But criminologist Charles Hayward has his doubts about the innocence of the entire Leonides brood. He knows them intimately. And he's certain that in a crooked house such as this one, no one's on the level.