Kain D'Mere is an early-middle aged Latharian assassin in service to vampire ruler Lady Kalifax. After nearly a quarter century of dedicated service his mistress, she charges the estranged, bitter genius Dr. Edmund Vargas to grant him wings. He does so, quickly and efficiently only so that he can use Kain as the vessel of her demise. After the loss of his love he becomes haunted by her memory and shunned by society from his modifications and hunted by Vargas as he's a loose-end from Kalifax's murder. Kain swears vengeance to this doctor who seals himself up in a castle building a mutant army to march across the land.