Doctor Who: All 40 Steven Moffat Episodes Ranked From Worst To Best

We're used to the Doctor overcoming improbable odds but his blindness creates a vulnerability he hasn't experienced hitherto, and consequently adds another dimension of drama that's in keeping with this episode.

The sonic sunglasses have proved so unpopular among fans to the extent that an online petition was created with the aim of getting rid of them, and maybe even banishing the sonic screwdriver! However cease your outrage for a moment keyboard warriors because our hero's wearable tech is of critical importance this time around.

The Doctor's affliction is handled with essential realism and gravitas; "Because the moment you tell Bill, it becomes real. And then you might actually have to deal with it". Whilst remaining true to the adventurous nature of the show; there's greater tension to the Monks' gradual reveal through the Doctor's eyes. They never look so good in the morning, indeed.

Nardole remarks that the holographic simulations are like "a really posh VR without a headset. Through there, those places, that's basically Grand Theft Auto" (that has to happen, by the way). Going through the library labyrinth is similar to playing a creepy new game where the dark and disquiet is punctuated by a dazzling white light, which Bill and Nardole calmly and curiously walk towards.

Think the vast majority of us (and that's being conservative) knew who was in the vault all along. Nevertheless the greatest mystery is the contrite Missy, a feeling of conflict that becomes more apparent later on in series 10.