Resident Evil 4/Chapter 3-2

Basilica
It appears that Ashley needs to be rescued again and, spoiler alert, it's not going to be the last time. She's a lot like Princess Peach that way.

There is another cutscene, your communicator is activated and you hear, not from Hunnigan, but from Salazar who has tapped into the channel. He doesn’t seem to know where Ashley went either but promises to look for her. In the meanwhile, he’s prepared a little surprise for you in the sewers.

The only way forward is the door on the right in the north hall, so go though.

Sewer
Get the two barrels and drop through the trap door to the sewer. As you continue there are sounds that tell you you’re not alone here.

Walk along the corridor until you get to the corner, then equip the rifle and aim down the next corridor. Zoom in and look a bit to the left to see what appears to be a cloud of mist; a scope will help with this. The mist is actually breath from a new enemy known as a Novistador. It's a giant insect that has the ability to make itself nearly invisible; the only thing you can see beside its breath is a kind of wispy, drool soaked beard. Occasionally you may catch the outline. Your rifle should kill it in one shot if you hit its head, but you're not always going to be able to spot them from a distance like this.

Get the creature's drop before it disappears; it's known as a Novistador Eye and it comes in three colors, Red, Green, and Blue. They're attachments for a treasure we haven't gotten yet and eventually you'll need two of each color, but you do get extras so feel free to sell any excess. Blue is the rarest and also gets the best price.

Go back and explore a side path to get a box. Continue around the corner to a pool, but snipe the two bugs waiting in the water below before going in. Get the drops, then collect a Velvet Blue and Handgun Ammo from the bottom and TMP ammo from a pipe. Climb out on the far side and go through the door.

You enter a room with four prison cells. There are actually three bugs in here so just hug the wall to the left for a bit. With the scope you can just see the tip of a beard in the skylight, but there is no clear shot. Another one turns out to be hiding in one of the cells and is out of view. Some new tactics are called for, so advance slowly until the one in the skylight drops down. You'll notice that the camouflage doesn't work when the creature is moving, so shoot with your shotgun or TMP while you can see it. If you lose track of it then back into a corner and watch for the splashes it makes, but also watch the ceiling since it can crawl on it as well. If it gets close then it may pounce on you, in which case you'll need to shake it off, or it may bite or vomit acid on you and the only thing you can do is shoot and heal.

Fight the second one in more or less the same way; watch for it to break through the cell door and shoot while it's visible. You can sneak up on the third on which is waiting in the corridor across from the door you came in. Go to the corner and snipe it before it notices you. Head back to the cells to search; if you do this before eliminating the third bug it may notice and attack. One cell is rusted shut, but get a Yellow Herb and Handgun Ammo in the southwest cell, an Incendiary Grenade in the southeast cell where the bug came out, and Shotgun Shells and "Luis' Memo" in the northeast cell.

Turns out that Luis isn't just an ex-cop but some kind of scientist because the memo talks about research into parasites that can control their hosts. (The creatures mentioned in the memo are real; see Dicrocoelium, Galactosomum and Leucochloridium.)

There is a pool of water to the south, but the no swimming rule is still in effect so the water must be drained before you can go that way. Follow the passage east, then south through some disused cells, to reach the sewer control room; making note of the hole in the ceiling as you go. Get two boxes and open the treasure chest to get the Butterfly Lamp. Put an eye of each color into the lamp if you've got them. There will be another lamp so still save at least one eye of each color when you get them.

Operate the wheel to drain the pool seen earlier. Open the door to start back, but now more bugs have appeared so you need to go carefully. Snipe one, maybe two, bugs in the hole in the ceiling. Continue along the passage an another bug will pop out of the cell that was rusted shut earlier, and yet another will drop down from the skylight. Drop into the pool and go through the gate, another Novistador may drop in behind you. Get the Velvet Blue next to the stair, then go up, get two barrels, and go through the door. (You may find more or fewer bugs than the ones listed here because the game isn't exactly the same on every runthrough.)

The next room has some nice, visible, swinging pendulums. The biggest danger with them is not waiting until the blades are all the past since touching any part of them will kill you. Just time your way through them, grab the Velvet Blue on the right and climb the ladder on the left. Get two barrels and go through the door which takes you to the balcony of the basilica.

Observation Hall

 * 1) When you regain control of Leon, head through the door to the right. Grab the ammo from the barrels near by, then drop down the ladder. Head down the hallway, and you'll hear something run then jump, but you won't be attacked yet. Head forward until you reach the hallway facing south, then stop. Take out the rifle, and aim toward the south end of the hallway.
 * 2) You'll see drool hanging from the air that marks one of the invisible acid-spewing bugs down here. Luckily, they're as susceptible to headshots as anything else in this game, so take it down with the rifle by aiming just above the visible drool. All the insects drop "Eye" gems, which you'll be able to combine with some other treasure later. Head slowly down the hallway, and keep an eye out for the drool of the insects.
 * 3) If one gets close to you, blast it away with the Shotgun, but otherwise try to snipe them wherever you can. Past the first one, there'll be a pool of water to the right, with two of them near the far ladder. You should be able to snipe both of them, so once they're dead hop down, and collect their eyes, the Handgun Ammo to the left, the Velvet Blue in the water, and the TMP rounds in the pipe, then climb up.
 * 4) Head through the door, and another one will be waiting for you in the hole in the ceiling. Another will come at you from down the hallway, which you probably won't get the opportunity to snipe. Check the cells to find some Handgun Ammo, a Yellow Herb, some Shotgun Shells, and a memo from Luis. Before you check the cells to the east, though, head around the hallway to the east to take out another bug; if you do him first, you should be able to snipe him. Follow the path through the cells to find a room with a wheel you can turn, and some boxes with Shotgun Shells and a Green Herb. In the treasure chest is a Butterfly Lamp, which you can combine with the Eyes you pick up from the bugs.
 * 5) Use the wheel to drain the water, then head back out to the main area. Be wary, because the bugs will have respawned now. There's two waiting for you in the hole in the ceiling just outside the room, and one in the main room, which'll come out of the one cell you couldn't open before, and one more which will drop at you from the ceiling.
 * 6) Hop down into the water, and kick down the gate. Yet another bug will drop down behind you when you do, so run into the next room, turn around and blast it. Grab the Velvet Blue in the corner, then head up the stairs. Continue on into the next area, and you'll see a bunch of pendulums swinging back and forth across the path. Just wait for them to pass as you go by them to avoid being chopped up.
 * 7) Grab the Velvet Blue on the other side of the blades, then head through the door. Climb the ladder, get the loot from the barrels, and head through the door. You'll stumble in on a little meeting of Ganados. If you've got any Grenades, toss one right in the middle of the group to take a bunch of them out at once. Hop across the first chandelier to the other side, then use the second one to head to the other section. Flip the switch here to open up all the grates, then finish off the red robed Ganado to get an Illuminados Pendant. In the northeast corner of the upstairs is an Elegant Mask, so make sure to grab it.
 * 8) If you don't kill them, they'll eventually spot you and head into the next area, and you'll lose all the loot you could have gotten. Save, then head up, sell the loot to the Merchant, and head through the door next to him.
 * 9) Head forward, and grab the Red Herb on the table, then head up the stairs to find a note from Salazar. Go through the green door to find a bunch of Ganados waiting to ambush you. These ones aren't quite so willing to chase you through the door, so first use the Rifle to take out the crossbow guys, then take out the ones wandering around the room. Grab the loot from the urns, then head through the door to the southwest.
 * 10) Once inside, grab the loot from the urns and head up the stairs to find another Ganado, then head through the door. Around the corner is some Rifle Ammo, so grab it then head around the catwalk. You'll be able to drop down here and engage the last couple Ganados, but when you do the red one will run away. Kill the two there, then give chase, making sure to grab the Shotgun Shells and Pesetas in the room he flees through.
 * 11) Through the green door in the corner, there'll be a shield Ganado to slow you down. Take him out and keep following the red guy. When you get to the door at the bottom, you'll find he's brought out a Gatling gun to attack you. Whatever you do here, don't give him a clear shot. Retreat back to the doorway to the catwalk, which'll give you enough cover to avoid his attack and let you snipe him. Once he's dead, go down and collect the Gallery Key.
 * 12) Head back to where the red Ganado was first standing, and use the key to get through the door. Shoot the deer's eye to get a Velvet Blue, then break the urns to get some Shotgun Shells. Go to the console in the middle of the room to start the puzzle.
 * 13) The objective here is to make it so six people are displayed in the four pictures. Switch 1 turns the two pictures on the left; Switch 2 turns all but the rightmost picture; Switch 3 turns all but the leftmost picture; and Switch 4 turns only the two pictures on the right. Hit the switches in this order: 1,4,3,2. Hit OK, then head through the now open door.
 * 14) You'll get another cutscene with Salazar, and then be attacked by more Ganados. Take them out, and if you need some cover head to the door directly to your right and use it as a bottleneck. You'll find a Yellow Herb at the top of the stairs here as well. As you fight them off, more crossbow wielders will come out, and eventually a pair with rocket launchers will fire at you from behind the painting, but mercifully only once.
 * 15) Clear out the room, then hit the red button on the wall in the alcove to the west. Now, head toward the small room in the south, and another pair of Ganados will launch rockets at you; just get behind cover, and continue to the room. Hit the button there, hidden under the urn, to extend the bridge. When you go back through the door, you'll find another pair of rocket launchers pointed at you, so just retreat through the door and let it take the blast, then take out the rocket launching ones (who'll die in one hit), and the three scythe-wielders who join them.
 * 16) Once that's all done with, grab the Goat Ornament from the chest, then head out through the door to the west. Save here, then head down the hallway. Grab the Handgun Ammo from the urn there, then head through the door to the west. Shoot the Spinel down from the wall, and continue on.
 * 17) Head down the walkway, and shoots the crows on the fountain to get some loot. There's a small room off to the side here that contains the Broken Butterfly, but you won't be able to get it until you get Ashley back later.

Salazar's Garden

 * 1) Take a left, and follow the path. Through a gate, you'll see a kennel with three wolves in it, some of which might mutate. Blast them all and collect whatever loot they drop. From here, head to the east and follow the path until you get to a treasure chest. A pair of wolves will come at you, so put them down, then head back to the west.
 * 2) Take the third right to find a Yellow Herb, then the second right. Head north until you reach an opening, take out the wolf here, then go south on the path to the right to find a treasure chest with a Red Gem. Now, head back out and go west, then up the stairs. From the fountain, grab the right half of the Moonstone.
 * 3) Head back down the stairs, and continue your sweep clockwise around the maze, taking out the dogs as you go. There's a First Aid spray in one alcove in the northwest corner, and a Spinel in the northern one. Once you've collected them, head back to the southeast corner and cross the walkway to reach the northeast corner, and grab the left half of the Moonstone from the fountain. Head back toward the door you passed which you needed the Moonstone for, and watch out for dogs.
 * 4) Combine the two halves, then use them on the door to open it up, and enjoy the cutscene that ends Chapter 3-2.