Resident Evil 4/Chapter 5-2

Secure storage
You're now in the storage room where Ashley was being kept prisoner. Grab the Shotgun Shells hear and start for the exit. Something flies in through the window, pick it up to get ”Paper Airplane”; it's from Ada and it's a clue to how to get out of the complex.

More soldiers are waiting outside the cell so leave Ashley inside and defeat them. A cheap way to do it is to shoot at them through the window in the door.

Head south back to the waste disposal area as Ada hinted.

Waste disposal
You immediately have to fight soldiers guarding the security panel; have Ashley stay in the entrance, then stun the soldiers that are approaching then snipe the archer and the battle is practically won. At some point a soldier will appear and shut the door to the waste disposal room, so now you need to open it again.

When you open the door more soldiers are going to come in through it, they're going to do it very quickly and they're going to come straight for you. So some prior planning is called for. First you need to find a safe place for Ashley, away from the action but far enough away from a door that she can't be carried off quickly. The best place is probably in the corner with the computers. (Maybe she can play some video games while she's waiting.)

Position yourself at the security panel so you're facing the door as much as possible, then activate the switch and before you know it the soldiers will be right in your face. A useful trick here is to interrupt the short cutscene showing the mercenaries entering the room; when you do this the mercenaries will still be entering the room rather than already surrounding you when you get control again. An Incendiary or Hand Grenade is dangerous to use when enemies are very close, but they may work if you can get the timing right. An alternative is to use a Flash Grenade to stun them, then get over to where Ashley is waiting and make a stand there. Yet another alternative is to just fight them where you are; in this case the TMP has the required combination of speed and firepower.

When the battle is over, go through the door you just opened head down the hall into the waste disposal room. There is a cutscene where you trust Ada’s message and jump into the garbage chute.