I cut the conversation short, reminded her again that if there is anything I could do I would do it, and hung up. Gina who had got the SET-UP from my expression said tactfully, "After all, she is the daughter of a millionaire."
"Setup" as a noun can be used to mean a configuration, or particular arrangement. For instance I could refer to the desk where my computer is kept, my desk chair, the sound system and all of its peripherals as my "gaming setup."
It has a slightly different meaning when used in context of social interactions. Instead of a previously-made arrangement of things, a setup is a previously-arranged strategy. In this particular instance, the narrator said a particular expression, possibly with some sort of special hint, that allowed Gina to pick up on the narrator's strategy and later act upon it.