Where is the Opera House?

Hint 1 of 5:

Do you know of anyone who has friend in the opera?

Hint 2 of 5:

Maybe even a sister?

Hint 3 of 5:

Sarah has something in her dressing room that will help you.

Hint 4 of 5:

You'll have to get into a place that only she had been able to get into.

Hint 5 of 5:

How about that locked drawer in her dressing room?  See the clues under
"Sarah's Boyfriend" if you can't get into it.