So, When she says in plain sight. The hint isn't in build buy but must be out in the world of San Sequoia. I'm thinking it might be a hint on the movie theatre. If she doesn't mean the piano having a hint on it.. I have to go see now.
Edit: Well, There's a big all seeing eye on the piano in San Myshuno. I tried to see if the eye was looking towards anything. lol You know being in plain sight.
The movie theatre has a movie called Death Mirror. Could it be a hint for the upcoming Black Mirror season on June 5. :D Since she won't confirm or deny. I guess we just have to wait it out.