Series Producer Challenges Fans to Figure Out Clara's Mystery

In an interview with TV & Satellite Week, series producer Marcus Wilson has challenged fans to figure out the mystery behind Clara.

What’s lovely this year is that we’ve also got a thread running through these eight very different, very exciting stories – the mystery of Clara. She’s the impossible girl. The Doctor has met her twice before and both times she died. This time he’s determined to keep her alive and to discover who or what she really is. It’s a riddle that won’t easily be cracked. I defy anybody to guess it. Steven Moffat has found a way to lead everybody down the garden path and then knock them over with surprise at the end.

It sounds like we're going to be given a giant red herring and won't really know the answer until the end. So it will basically be impossible to figure it out until the end. That doesn't mean we can't try, though.