I am loving the Lorien book series. The power of Six expands on the story started in I am Number Four and introduces us to new members of the Garde: Number 7 (Marina), Ella (effectively number 10) and Number 9. It also continues the story of John and Sam after they leave Paradise. It takes place in 2 different locations at the same time, one part told by John and the other told by Marina. Two separate journeys that will eventually lead the two groups back together, though not until a future book.