If they refuse to tell you the nature of the discussion then you are under no ethical (or legal) obligation to visit them.
If it isn't important to them, you won't hear from them ever again and the problem will be solved.
If it is important to them, they will either provide you with more information (which you can use to make a more informed decision) or they will come to see YOU which makes it irrelevant whether or not you went to see them in the first place.
In any case, if they ask you any questions that make you feel uncomfortable, such as questions about yourself or about your past behavior, you always have a constitutional right to keep quiet and consult a lawyer.
Thanks. I like that advice