Doctor Who Series 10: 6 Theories On Who's In The Vault

While there is a good chance that John Simm's Master is in the vault, the most likely candidate has to be his successor Missy. Let's stack up the evidence, shall we?

In Knock Knock, the Doctor spoke to his prisoner while they were playing the piano. In the season ten trailer, Missy was seen laying on some raised surface in what looked to be a glass prison. What's the betting that she was laying on top of her piano inside the vault? Not to mention that the vault prisoner was seemingly delighted with the idea of being told a story about people dying in that same scene. Who else does that sound like other than Missy?

According to another fan theory, Steven Moffat has apparently turned to a poem written in 1681 for inspiration. Andrew Marvell's To A Coy Mistress has spawned two of the show's recent episode titles - 2015's Before the Flood and the upcoming penultimate season ten episode World Enough and Time. Could it be that Moffat has been deliberately drawing from the poem to provide us with a hint as to who is in the vault? Notice the title: To a Coy Mistress.

To be honest, that last one might be stretching it a bit, but it is an interesting detail nonetheless. The biggest piece of evidence is surely the fact that Missy will appear in Extremis, the episode that we know will reveal who is in the vault. Coincidence? Not a chance.

Who do you think will be in the vault? Missy? Omega? Adric? All theories are welcome in the comments secton below!