The invitation

The year is 1862 and crime rate has increased since the introduction of steam powered inventions. Celestine, an investigative reporter, coming back to her room in the Cozy Hearth Inn after investigating The Elite at the Libary, finds an invitation to a maked ball on her desk. The Invitation reads: "Celestine, You are here by summoned to attend our bi monthly masked ball event this upcomung Tuesday. This one is being hosted by the Grey Estate. This months theme is Roses. Attendance is mandatory, as we have something that belongs to you. We look forward to seeing you there. E." Inside the envelope that contained the invitation, there is a single rose petal covered in blood. With the masked ball happening next tuesday, it'll give Celestine almost a week to figure out what her next move is. To prepare. Who is E? What have they got that belongs to Celestine?