You are in an underground facility when suddenly hell broke out, the alarm is turned on, you heard gun shots and yelling everywhere, after a couple hours everything went silent, suddenly an infected fell from the vents, you aim your gun at it but its jammed, but then the infected is shot multiple times before dying

"You good?"

Said the Signaler, while aiming his gun at the corpse

"Where's your squad?"

He asked, and you told him that your squad is wiped out, he then sigh

"You and Me, we're going out of this clusterfuck of a facility"