This context comes from the video game "Metal Gear Solid The Phantom Pain"
"He went to incredible lengths to make sure his "great escape" went unnoticed. So far, I know at least Langley and the Pentagon were involved. He had a blackout triggered in New York to disrupt the transportation and information grids, and at least two submarines were sighted off the coast. The personnel involved were working off a cover story. Naturally, the White House was fed the same thing.The project is buried under a pile of dummy ops and backup plans stretching across multiple organizations. It's safe to say not one of the people involved knew what they were moving or where. All top secret. No trail, no leads. "
"work off" 2. To use something or someone as a foundation or source of energy to perform work: This laptop works off batteries. I worked off my strengths as a writer to convince the newspaper to hire me. See also: off, work(source:The American Heritage® Dictionary of Phrasal Verbs)
"work off" 5. To use something as a template or point of guidance. Architects worked off the original 12th-century drawings to authentically recreate the Gothic cathedral. Hey, I'm just working off the instructions they gave me—it's not my fault if something is wrong!(source:Farlex Dictionary of Idioms. © 2022)
Does it mean that the staff was using this fake story about the nature of their job as a source of motivation/point of guidance so that even they didn't know about the actual job they were doing? Is any of the definitions I provided relevant?