NOT SURE WHAT TO PUT THIS UNDER!!
Okay! So, I just watched Phantom of the Opera movie for the first time and while I was watching it, a thought came to me.
What if one of the Doctor's companions wanted to go the opera house where the phantom supposedly was, so he takes them to that era and they go to watch a show. Suddenly they hear a scream and the Doctor, being the Doctor, runs to check it out? When he arrives, he finds a body hanging from a rope. The companion, just arriving, hears a comment along the lines of, "It's the Phantom again," and gets excited. Cue adventure
Sometime later in the episode, the companion discovers the phantom's cave and gets trapped. Cue the Doctor trying to save them.
The phantom turns out to be an alien, (What?! That wasn't obvious at all.) and the Doctor names the species, etc. etc., and saves the companion. Then he helps the alien get home.
Long thought, I know. But what do you guys think? (Now that I think of it, it's more fanfic material than show material. Oh, well.)