This one is shorter than Upside Down, but waaay hotter! I am glad to find out that Tanner is not the jackass everyone thought he was. You could probably read this before reading Upside Down, but I would recommend reading it first. Maybe it is just because I didn't read this one without first reading Upside Down, that I just can't imagine one without the other, I'm just weird like that sometimes. Anyways, this book is short and sweet. I can't wait to read the rest in the series! This is a total MUST READ!!!