I Am Number Four: The Lost Files: Hidden Enemy is the third collection of action-packed novellas from Pittacus Lore. Initially published separately as digital originals, these three stories are now together in one print volume. You know the truth about the Mogadorians' invasion of Earth and the Garde who will do anything to defeat them--yet there is still so much to learn. The stories in Hidden Enemy will help you get the answers you seek, but they will not help you stop the coming war. Only the Garde can save our planet.The I Am Number Four series is perfect for fans of science fiction adventures like the Fifth Wave series by Rick Yancey and the Beautiful Minds series by Alexandra Bracken.