I have this thing about reading post-apocalyptic novels. I love to read about humans trying to survive as our world is being wiped out. I know it sounds absurd and depressing but I like to think I am rooting for the good guy. I want someone to win, I want someone to outsmart the bad guy and overcome the death of society and come out on top. So when I came across this book by Rick Yancey and read that there were 5 waves, yes 5 that humanity had a chance of beating, I was thrilled. So why didn’t everyone die during the 1st wave and even the second? Were these individuals smarter than the rest of society? Were they the “preppers” we all hear about or did they have special training to keep them alive? Plus the cover of the book was terrific too!Cassie thinks that the “unlucky” ones are the ones who survived and I guess if you were living in her conditions you might have to agree. Her safe world with her family is now shattered and living in the trees is the safest place for her right now. But she has made promises and she must abandon her safe spot and push herself to move forward to fulfill her promises. Trusting no one, she is alone. Above her now are not the comforts of her parents loving embrace but the Mothership. Yes, they have arrived. The aliens, the Others, whatever you want to call them, they have reached Earth and have eliminated the humans in vast numbers. They are attacking in Waves and the fourth Wave was the latest. And Cassie, she is one of the “unlucky” ones. What do they want and when will they quit? As Cassie tries to fulfill her promises, she finds out more about the Mothership and the waves. She encounters individuals but yet she knows she must trust no one. As she moves forward, Cassie learns about her future and her past and who she really is. Can she fulfill her promise and what will become of her world?The premise behind the book was superb. Cassie made promises and she felt that she must fulfill those promises no matter what and that gave her determination and strength. How the other characters came into play was an interesting twist in the story and the ending was fantastic. I thought there was a bit too much romance for me in the story and the middle of the book got a bit slow for me. The beginning and the ending of the book was fast-paced and pulled me though on quite an adventure. The nicknames the characters were given added a personal touch to the story as did some of the conversations between the characters (don’t want to add spoilers here). I’m glad that I read this novel and I would recommend it. "The Hum is gone. You remember the Hum. Unless you grew up on top of a mountain or lived in a cave your whole life, the Hum was always around you. That's what life was. It was the sea we swam in. The constant sound of all the things we built to make life easy and a little less boring. The mechanical sound. The electronic symphony. The Hum of all our things and all of us. Gone." (great quote and something I could relate to)