First get to the silver case open it then kill everyone but dont go in the hole go back where the case was and turn right and crouch, somewhere there is a grey thing next to some fire go through it and keep crouching go through the wall and there will be some of your enemy's legs but you wont be able to kill them keep going until you see a boat with a cow the golden gun is behind the cow you can shoot the cow and it will make noises but there is no more secret places around there so come back and shoot your enemys! it will only take one shot then they're are dead!