This episode and story line held so much promise, but the juvenile Disneyesque production, including a horrible musical dance scene was more Micky Mouse Club than Sci Fi.  It felt like teenaged writers just threw flashy ideas at a camera and ruined the story.  This Doctor and Ruby matched against a wonderful villain with a horrifying theft of music, was simply ruined by adolescent writing and horrific production.  This is probably my least favorite episode in the 60+ years of the show... Just Awful.  It's particularly sad because it could have been Oh so good.