Finished Book #4

I finally finished World War Z last night. Some parts were exciting and some could not hold my attention at all. I haven't had anytime to read during the day, so I've been reading right before bed. This book made me fall asleep after about 10 minutes, so that's why it took me about a month to read it. I really don't know what happened in this book. I feel like I should know what "Zack" means, but I don't....