An unexpected twist - Certain that his father's recent late meetings and cancelled plans with the family means that his father is up to his old tricks and cheating on his mother, your character agrees to an internship that he had turned down for months in order to keep an eye on his father. Once his meets Miss Franklin, his father's new personal assistant, he is positive that she is the one his father is now bedding. His attention turns to her and he soon realizes that she is up to something but it isn't screwing his dad. At least, not in that sense.
My character, Miss Franklin, is in fact working with one of the men in accounting to bilk the company out of as much money as they can. She has been feeding him information for months and gets caught snooping around the father's office in search of a document that has the account numbers she needs to set up the biggest score yet. Your character isn't certain exactly what she is up to but is quick witted enough to blackmail her, convincing her that he knows everything and the only way to stop him from turning her in to the company and the police is to do whatever he wants.