The Wolves of London - Obsidian Heart book 1 (Obsidian Heart)

Psychology professor Alex Locke is an ex-convict who is forced back into the criminal underworld when his daughter is threatened. After agreeing to steal a mysterious Obsidian Heart, Locke finds himself relentlessly pursued by a band of unearthly assassins known as the 'Wolves of London'. Locke soon learns that the heart has the ability to transport him through time, and while it bestows him with his own dark power, it also corrupts.