The Black Crypt is home to the Zombies (dangerous and 'undead').  As long as the 'Holy Book' is upon the Crypt's high altar, the power of the zombies is limited, and they are prevented from leaving their tomb.  However, the Holy Book has been removed and the Zombies are on the rampage, terrorising the locals.  Your mission: take the Holy Book back inside the Zombies' crypt and place it upon the high altar.  Warning: the Zombies will kill to stop you!