When you first walk in, go down the stairs and to your right. There is a holy water bowl. Fill up your gun, then open the door, battle the monster, and get rid of the phantoms blocking you. Walk through the door and battle the next two dudes. On your right is an open wall with a hellfire vail in it. Then go down the ladder and here is the secret. Go down the stairs on the right then go around the corner to he right and look at the wall. You will see something glowing in the wall. If the vamp comes out first, defeat him then go to the wall, have your reaper out from the vamp(if he came out) and smash the wall where the glowing object is. It will be the only secret in here and it is a holy water vail just for you!