Like so many good heist movies, Flawless presents us with a seemingly unsolvable puzzle, lets us stew over it for a while, then solves it for us. The puzzle is of the "How did Person X manage to accomplish Task Y?" variety, and it is indeed a head-scratcher. I wish the film came up with an answer that was anywhere near as ingenious as the question, but it's a generally satisfying story anyway.
The setting is a diamond company in London in 1960, where Laura Quinn (Demi Moore) is a senior negotiator with bruises on her head from constantly bumping into the glass ceiling. An American girl, she has lived in England since attending Oxford (and seems to have halfheartedly picked up a mild British accent along the way), she's essentially married to her job, and she's frustrated at being passed over for promotions.
She's friendly with the night janitor, Mr. Hobbs (Michael Caine), a cheeky old widower. I don't recall whether he ever calls anyone "guv'nor," but he seems like the type. The fact that executives ignore him when he's around makes him privy to a lot of delicate information, and he warns Laura after overhearing that the bosses plan to use her as a scapegoat. All her loyalty and hard work, and now she's going to be hung out to dry.