Demon games - Steve Feasey

Teenage werewolf Trey is facing the most important and dangerous mission of his life. He must journey into the dark Netherworld and rescue Alexa, daughter of his vampire guardian Lucien, who is being held hostage by a powerful demon lord. But strength and courage alone are not enough to succeed - instead Trey must 'win' both their freedoms by participating in a death-match against his deadliest nemesis yet. The forces of evil are stacked against him and Trey can only be certain of one thing . . . one of them WILL die.