The Inheritance Games is a YA mystery/thriller. I checked my copy out from the library.
Review:
Avery Grambs is a smart teen who's determined to build a better life for herself. That means getting out of high school, winning a scholarship, entering a good actuarial science program, and hopefully starting a well-paying career. And then billionaire Tobias Hawthorne dies and changes all of Avery's plans in an instant when his will reveals that he left her nearly his entire fortune. The only catch is that she must live in his mansion with the family members who were just disinherited.
Avery has no idea why a billionaire with no connection to her would have left her his fortune, and most of Tobias' surviving family members are understandably less than friendly. However, there are indications that Tobias left answers behind, hidden behind a series of riddles, codes, and secret passages. Unfortunately, the ones best suited to solving the puzzles Tobias left behind are his grandsons, who are definitely keeping secrets from her and have no real reason to help her.

