Lila, Leo, and Milo thought they had uncovered the biggest secret in the penthouse. They were wrong. When strange clues begin appearing inside the hidden room, the siblings discover that Aria left behind more than old letters and music. Someone has been there recently. and they may not be alone. As the mystery spreads beyond the penthouse and into Opera City, the Anderson kids must solve hidden puzzles, follow secret messages, and uncover the truth before the room and its secrets disappear forever.
Lila, Leo, and Milo thought they had uncovered the biggest secret in the penthouse. They were wrong. When strange clues begin appearing inside the hidden room, the siblings discover that Aria left behind more than old letters and music. Someone has been there recently. and they may not be alone. As the mystery spreads beyond the penthouse and into Opera City, the Anderson kids must solve hidden puzzles, follow secret messages, and uncover the truth before the room and its secrets disappear forever.