Layton receives a letter from the famed opera singer Jenis Quatlane, inviting him to attend her newest performance. She also asks Layton, Luke, and Remi for help with a mystery: her friend Melina died a year ago, but later returned as a seven‑year‑old girl claiming to have discovered the secret of eternal life and to know all the secrets that only the true Melina could possess. Naturally fascinated, Layton and his apprentice set off for the Crown Petone opera house, while Remi stays in London to investigate a group of missing girls linked to the venue. The opera is set in the lost Kingdom of the Immortals, where a beautiful queen who loved music was beloved by everyone in the realm.