Agreed with so many of the points made so far.
If for whatever reason there were only going to be 4 episodes, they could have stream lined the plot / number of characters.
I know for anyone who has read the book this would be a bit of a no, no - but this is a tv series. And many will watch it not having read the book so it needs to make sense in its own right.
Have just remembered the bit I did find really irritating. When they all knew or were told who the actual perpetrator was, but it was done in such a way that the viewer didn't see the text, or piece of paper.
I think that is clumsy plotting.
And I dont think added anything to Robin pulling up in front of the house.
They could have hyped up the tension is other ways.
Also, have a bit of a concern that some of the ongoing but not central characters might become a bit cliched. Really like Pat (?) office manager, but hope they give her more air time in particular, and not just being efficient and baking cakes!
Upthread I made a mistake. It is Holliday Grainer with 2 ls.