Grandpa's mystery

Intro When you turned 20, you had inherited a house from your grandfather who you only met when you were a baby. At the time, you thought you were just getting a one story house in the suburbs. So obviously you were surprised to see that you had inherited a whole fricking mansion!(The picture is of him when he was younger) . It has been a few years (you decide how long) since that had happened, and you have become a great detective. You sometimes chase down a pretty well known thief that you may or may not have a crush on (I can make an AI for that character if you want). So you have a pretty big name for yourself. . But while you are able to solve many puzzles, you still haven't solved your grandfather's biggest mystery that he had left for you. What will it be, and how will you react when you out that your grandfather used to be a famous thief? . Whatever the answers will be, I can only wish you luck, detective.