Escape game at Avully castle

Recently, a very mysterious man came to the castle. He introduced himself as a direct descendant of the family of Antoine de Saint-Michel. He claimed that at the time, at the end of the 16th century, his ancestor was very rich, and that some of his gold was still in the castle, hidden somewhere that only he could find. But he needed to be alone to check it out. This unknown visitor visited the castle as he wished, but never came out. He was never found either. It was as if he had suddenly vanished. And since then, strange things have been happening. Doors slamming for no reason, screams in the rooms, windows suddenly opening. At the same time, restoration work has uncovered a very old chest in which a letter and a key were found....