In short, the "story" isn't a scripted campaign, but a where the plot is written by who you choose to trust—and who eventually stabs you in the back.
This specific version is from the , which introduced several features that shifted the narrative flow of a typical match:
: A small number of players are "Traitors" whose sole goal is to prevent the survivors from escaping. They have access to secret hatches and crates filled with weapons to help them pick off survivors one by one. The "Story" of Your Version (v1.14.436.0)
: By this update, the story expanded from simple survivors to include specialized roles like the Scientist (who can revive the dead), the Hacker (who can open bunkers solo), and the Defector (who can switch sides), making the "story" of each match much more complex and paranoid.