The Gatekeepers8 books in series
The Power of Five: Raven's Gate Publisher's Summary
The first episode in The Power of Five series by the author of the best-selling Alex Rider series, Anthony Horowitz.
Matt has always known he has unusual powers. Raised in foster care, he is sent to Yorkshire on a rehabilitation programme, only to find himself in the midst of sinister goings-on. Matt investigates and uncovers a terrible secret - eight guardians are protecting the world from the Old Ones, beings banished long ago by five children. But devil worshippers want to let the Old Ones back in....