Reading this as a play as well, and for some reason, because it was a stage production, Hercule Poirot is entirely absent from this telling of the story. As such, the detective isn't introduced until the third act of the play, and we're instead just witnessing the dynamics and actions of the characters throughout the first two acts without a clear perspective on who will ultimately clear up the mystery.

That being said, the dynamics are most interesting, especially given the time period they are set in. Equally interesting is the character of Lady Westholme, who we nowadays we would classically know as an upper-class white feminist, campaigning for equal pay for women, but calling the tour guide by the name she gives him, instead of his actual name.