As mysteries go the cliché ridden
haunted house story is full of them, and Mike Bartlett’s debut Doctor Who
episode Knock Knock is no exception. This deceptively simple tale, filled with
many unanswered questions, hints at Bill’s desire to have a life outside the
TARDIS as well as the Doctor’s reluctance to leave her alone.
The Doctor ought to be guarding that mysterious vault of his, as Nardole would no doubt be telling him, but instead he seems determined to keep a close watch on Bill. Good job too if this latest episode is anything to go by. With or without the Doctor, Bill seems destined not to have an ordinary student life.
We are a long way from the rift in Cardiff and as far as we know, in a welcome break from recent companions, Bill’s backstory is unexceptional. So why are alien forces at work in Bristol, seemingly independent of the Doctor and the TARDIS?
It’s unlikely that we’ll get an answer to such a question, for if such coincidences didn’t happen we’d be left without a story worth telling, but from the allusions to past Doctor Who adventures to the contents of the vault there are plenty of things we can reasonably conclude.