Darkside (Darkside Series #1) by Tom Becker
Jonathan Starling's father is in an asylum and his home has been attacked when, while running away from kidnappers, he stumbles upon Darkside, a terrifying and hidden part of London ruled by the descendants of Jack the Ripper. The Darkside is a place where vampires and werewolves walk the streets. It's a world of nightmares and deadly secrets. Jonathan is in mortal danger if he cannot find the way out.