Resident Evil 4/Chapter 3-2

Observation Hall
The radio transmission you get from Salazar will give you a hint of what's to come. After the transmission, turn around and head through the door.

Prison Area
Break the barrels for items, go around the corner, and drop down. Walk along the corridor until you get to the corner. Equip the rifle, and aim down the next corridor. The mist is actually breath from a new enemy known as a Novistador. Shoot the area where the breath originates to kill the creature in one shot. Now you can move down the corridor safely. Ignore the hole in the wall to the right, and be sure to pick up the item the creature drops; it's a new treasure known as a Novistador Eye, and it comes in three colors, Red, Green, and Blue. Move into the next area and snipe the two bugs waiting in the water below. Drop into the pool and collect the items there, then climb the ladder on the other side. Open the next door, and watch out for the Novistador that drops down from the skylight. Use your shotgun to deal with it. Once the first one is dead, another will attack from the left. Deal with it, collect the Eyes they drop, and walk down the corridor to the left.

Another bug is waiting on the right, so blast it with the shotgun before it can attack. Head back to the central area and search each cell for items and a document. Investigate the area full of water, then head back down the corridor, move through the destroyed cells, and enter the room at the end. Break the crates here and open the red chest to find a Butterfly Lamp, a treasure that you can combine with Novistador Eyes of three different colors to increase its value. Turn the red valve to drain the water. Open the door, but don't move forward. A Novistador is hanging from the ceiling ahead. Snipe it, then move forward and snipe the one waiting in the destroyed cells.

When you get back to the central area, another Novistador will attack from a cell across from you. Deal with it, then head back to the corridor where you killed the first Novistador. Head back to the hole in the wall, where another Novistador has appeared at the end of the small passage inside. Snipe it, collect its Eye, and break the crate here. Return to the central area and drop into the lower area. Another Novistador will drop in behind you. Run up the stairs to narrow its path of approach, and blast it with the shotgun when it's close. Grab the Velvet Blue from the drain, and break the barrels at the top of the stairs for items. In the next area, move between the swinging blades as they pass in front of you, and jump the gap ahead using the same timing. Grab the Velvet Blue, then climb the ladder, smash the barrels here, and exit through the door.