The protagonist is a young woman who inherits a mysterious key from her grandfather. He tells her that the key unlocks a secret room in his house that he's never been able to find. Intrigued, the protagonist sets out to find the room and unlock its secrets.
As she searches the house, she discovers clues and hidden messages that lead her on a scavenger hunt through her grandfather's past. Along the way, she learns about his life, his loves, and his regrets. She also discovers a family secret that changes everything she thought she knew about her ancestry.
As she finally unlocks the secret room, she discovers a dusty old trunk filled with treasures and mementos from her grandfather's life. But more than that, she finds a letter addressed to her, explaining why he kept the room a secret and what he hopes she will do with the key and its contents.