The first thing that drew me in was the title. Three are dead, I am Number Four. That sounds so cool. And this book didn't disappoint.
Fourteen/fifteen years ago, Lorien was ravaged by war, waged on them by the Mogadorians. Only a few escaped: Nine children, and nine guardians. Eighteen people, all that is left of a civilisation. They came to Earth. There was a charm placed on them, that they could only be killed in the order of their numbers 1-9 (I feel really sorry for number 1). They caught number one in Malaysia. Number two in England, and number three in Kenya. And they will stop at nothing to get to Number four as well.
The book starts at number three's death. Then it goes on to tell the story from Four's point of view. He moves around alot with Henri, his Cepan, his guardian. This time, he's going to Paradise, Ohio. There his world i turned upside down. He meets a best friend, has a girlfriend, and doesn't want to move again. But he'll have to, sooner or later. There's nothing to stop the Mogadorians from coming to kill him now.
But the Mogadorians will have to hurry. The six that are left are getting stronger, developing their Legacies (special powers).
And when they do, the Mogadorians will have to watch out. They are ready to avenge Lorien, and save Earth.
I liked both Sam and Sarah as well as Number Four (who is going by the name of John Smith. I liked how Sam was obsessed by aliens and the fact that they abducted his father. And Sarah was a good girlfriend character. She was smart and pretty and strong.
This book is amazing. It's got nothing on the movie (I didn't like how they made Henri such a warrior, it didn't seem like him). I DEFINITELY recommend it to everyone.