Shadow Born - Shadow Born Trilogy, #1

Discovered wandering alone in the woods at night. Taken to a secretive mansion. 12-year-old Gabriel Frost has amnesia. He has no clue where he came from, how he received the scars on his back, or where he learned the assassin-like skills he seems to possess. His entire life is a mystery. Gabriel is about to find out the world is nothing like he believed: assassins, monsters, and new super technologies bridge the gap between our world and the shadow world.
But what other sinister secrets are his new guardians hiding? Who are the shadowfriends, and what do they want? Can anyone he knows be trusted? What if Gabriel has a few secrets of his own?Gabriel must unravel the mystery of his past before the monsters of the present destroy him.