"One of Reed's closest allies has a secret, and it could destroy any chance Reed and his friends have of ever escaping the island. This person hasn't been what they've seemed since the very beginning, and will do anything they can to stop Reed and the others from leaving." --
It's not a stand alone. It leaves you wanting the next book, and it would be beneficial to read the 3 books before it. The series may be a hit with reluctant high school readers.