I am always incredulous when a person who has murdered several people without blinking finally has the heroine in his power and instead of dispatching her neatly he ties her up.And even says “Now, my pretty, I am I going to take my time in thinking up a good way to kill you.”Unless he was a psychopath to begin with, he’d want any hindrance to his escape out of his way as quickly as possible. She'd be gone. The book would be shorter and it wouldn't be a series.