This encounter is found in a location called "Convention Center Hall D" in San Diego, California. Near the "San Diego International Auto Show"
You receive a warning at the very beginning of the encounter in the form of writing on the door. It tells you there are thousands of Zed inside, and that it's not worth it. It's not kidding about how many are inside, but it is worth it, if you are prepared.
Do not do this encounter unprepared.
(It is preferred if you play this encounter to this)
It's best to wait until you have a good team, good armor, and preferably after the Theater, where you find 23 grenades, as well as after Wild Turkey and Frannie's Farm, where you have the opportunity to get the missile launcher. You'll need it.
You will frequently be offered the chance to turn back as you fight your way through zed and search for weapons and ammo. There is a lot of military grade armor and weaponry here.
Eventually, you will reach a point where you see the following two messages:
- At the top: "You gather what weapons you can, but now you must either choose to stay and fight or try and get out. There are hundreds of undead closing in on you."
- In the text box: "It will not be possible to escape if you don't do so now."
They aren't kidding. You MUST select "Fight Your Way Out", or there will be a never ending horde of undead attacking you. If you select "Hold Your Ground!" You will have to either force quit or die.