Can someone tell me exactly what THE HOST, by Stephenie Meyer is about?

i really liked it i just finished it yesterday and it was about Wanderer or "Wanda" who is a soul who invades Melanie, a humans body and she refuses to go away. they are always having internal conversations and fighting but eventually they become friends. Melanie has memories that play in Wanda's head about the guy she loved and her brother from before she was "changed". They both set out to the desert to find them and her crazy uncle Jeb. I cant really give the rest away but it is an awesome book and i highly recommend it for anyone who is at least 15 or has a good comprehension level because some of it is very confusing. if you can get past the first few chapters without being completely lost then it will be good. if you decide to read it and have any questions feel free to email me. :)