Once a writer sends her stuff into the world, there's only so much control she has. Selling film rights might best be done with regard to how they will be handled, and not just in trade for a peerage.
That's because they will suffer a fate like this.
Rendell is one of the few writers who understands mystery, and who has helped reinvent the genre for modern tastes, including the cinematic vocabulary in literature. She's actually pretty good. But what she did was sell the rights to all her works in one package, which has then been sold to the public as Ruth Rendell Mysteries.
Well, this little story is not a mystery. Not close. It may have been an interesting read. I haven't read it, but can well imagine how she handled the internals of these characters. The producers have a hungry beast to feed, however that nasty time slot of a fixed length that needs to be filled every week.
So they stretch this thing, reshaping it in the process to something rather unwatchable. The only thing that can be said is that the story makes sense. That's rare for TeeVee, but hardly enough for anyone to waste time with this.
Ted's Evaluation -- 1 of 3: You can find something better to do with this part of your life.