The Murder of Roger Ackroyd was, I believe, the first Agatha Christie I read, so many years ago it's frightening. I do remember a lot about it, though, and watched this episode with great anticipation.
Unlike some on this board, I couldn't possibly remember some of the book details that were left out, but I knew something was missing. The book packed such a wallop, it was breathtaking.
This episode, alas, seemed ordinary to me.
Hercule Poirot has retired to King's Abbott and is working on growing marrow. When a friend of his, Roger Ackroyd, is found murdered in his home, Poirot looks into the case. Inspector Japp joins him, so the to old friends are reunited.
Just the day before, there had been the suicide of Mrs. Dorothy Ferrars. She was Roger's great love. Poirot begrudgingly is pulled further into the case, where he tries to figure out the motive as he sorts through suspects: a secretly married couple, Mrs. Ackroyd, etc.
From the beginning, Poirot reads a journal, the journal of the murderer. In the book, the story is narrated by someone else. Also, there is no second murder. Japp was not present; it was an antagonistic inspector. Poirot's actual Hastings in this story was Dr. Sheppard, who has a small role here.
What a shame -- of all the stories to wreck, this is the one they picked. I'm a little disappointed in the Christie estate. They sold these stories without any care of what would happen to them.
I loved Suchet, as always, and Japp.