Halo #2: The Flood Book

In order to understand this book, you have to read the first book in the series and play the Xbox game Halo: Combat Evolved. Even if you don't get it half the time, it's a good read!

This book is set in 2552, in the middle of a great war between humanity and a collective of alien races calling themselves the Covenant. This war reaches its peak intensity when a human ship discovers an ancient ring-world named Halo (hence the name of the book). The ship crashes there, and among the survivors is SPARTAN-117, the Master Chief. He is a bioligically enhanced cyborg-soldier clad in special armor. He traverses the ring with the remaining Marines, fighting the Covenant and unlocking the secrets of the ring. But when the Master Chief finds a subterranean laboratory in the middle of a swamp, the galaxie's greatest horror is unleashed . . .

Read it for yourself, and discover why this book is called "The Flood". To this day, I still have nightmares about them. When you read this book, you will, too.