Although it's best to read the first book before you read this one, you could still read this one by itself.
Max and her flock are half bird so they have wings and other special abilities. This is due to the fact that scientists had tinkered with their genetic material. The characters are Max, Iggy, Fang, the Gasman, Nudge and Angel. All of them are special in their own way, and some of them have special abilities. Max can fly extremly fast. the Gasman can imitate voices well. Nudge can sense things about the people who have handled things that she touches so she's great with computers. Angel can read minds and influence thoughts.
Max and the Flock try to live a somewhat normal life, and try to find their parents. However, the scientists at the lab they came from are still after them. It has a lot of complicated twists, involving things like the plans of Ari, Max's so called brother and "Eraser," half human and half wolf, so this book is really hard to describe, but easy and great to read. To get a better idea of what it's about, read an excerpt somewhere.
Max is really a great character that anyone will connect to. She has a great atitude and is really funny. The book is really surprising and a great read anytime.