Snowstorms in a Hot Climate

I read this book because I loved Sarah Dunant's The Birth of Venus. Snowstorms in a Hot Climate was a quick read - I read it in about two or three days...the kind of book that keeps you interested through tense scenes and action. But, like The Birth of Venus, the ending was kind of a dud. I like her writing style and the way she illustrated a long term friendship between two women that originated when they were girls - but something about it just seemed hollow to me. My question is whether she had a friendship like that to model this relationship on, or did she just guess? Having a very important friendship myself that goes back to seventh grade...her version just didn't ring true. (book#15)