Cara is an overachiever. She has to be first at everything. Unfortunately first place lands her as the ambassador to the first alien student to visit Earth, Aelyx. It is something she does NOT want to do. But, being Cara, she resolves to do it the best of her ability (read as: it'll look kick ass on her resume). However, Aelyx is not what she expected and she finds more in common with him as she expected. She strives to keep relations with her peers as Alien resentment rises on Earth. She must choose between her people (like species, literally), or the relationship and trust she has begun to develop with Aelyx.
I really did not like Cara. She is that girl at school (we all know one, don't even lie) that will step on anyone and everyone to get what she wants. Aelyx isn't an angel himself either though. He is convinced allying with the humans is a terrible idea and has hell-bent on making sure this Earth-Alien exchange is disastrous. Little by little, they see the humanity, or whatever, in each other and learn maybe there is something worth saving and loving in the other race.
The romance takes a back seat when they find out this Alien-Earthling exchange student program isn't as innocent as they think. Earth's government is hiding something big and it could effect the everything the aliens are working towards as well as the lives of everyone on Earth. THAT part was interesting. The romance? Eh, I've read twilight, don't really need that much more. Granted, Aelyx was much more moody and hateful until Cara gave him a reason to prove otherwise. So, I guess that was nice.