Book Title :   Raven's Gate
Author :        Anthony Horowitz
Genre :          Sci Fi

brilliantly imaginative 

technological spy worlds (Mr Kelly)

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...