I need to tell you straight away that this thriller is not for the squeamish. Without giving a spoiler, I can't give you the reason but please be aware some readers may be revolted by the exposed crimes.
However, the reason I was engrossed by the story is that I didn't see where it was going until near the end. That's always the sign of a great plot, I think. I thought I knew what the crime would be, since it was set in a care home, but I was wrong.
You can read more about The Exit by Helen Fitzgerald on Goodreads.