Vampires and werewolves have been blood enemies for centureies, but now a new threat is rising... demons are escaping from hell and those demons are intent on wiping out both the vamps and the werewolves. 

In order to stop the demons, pureblood Royal vampire Kyuhyun agrees to the treaty offered by werewolf alpha Siwon.  Kyuhyun will mate with the alpha werewolf, share his blood and in return, the wolves will aid the vampires in this battle. 

But Kyuhyun doesn't realise just how dangerous the wolves can truly be.  Siwon has been waiting years to claim him.  He's set a trap for his vampire, and now that he has Kyuhyun, Siwon doesn't plan to let him go.  He'll send the demons back to hell, and he'll keep his vampire...forever.