Ok I found the plot a bit slow to begin with. It took a few episodes to really get into the story, but it was always intriguing enough to keep me watching.
The protagonist, Grace, is very likable. She's smart and hardworking but she's monotonous. The actress does a good job portraying her, but at times I found her acting mediocre.
I would think the objective was to show how Grace's interactions with different characters contributed to the events leading up to the murders, like all the abuse, disrespect, etc. And you really develope a sense to why such a thing could happen. You really "feel" with Grace as you get to know her throughout the story.
Overall, I enjoyed the show.