[caption id="attachment_144709" align="aligncenter" width="976"] Doctor Who: "The Witch's Familiar" (Photo: BBC)[/caption]

Assuming you have seen the latest episode of Doctor Who and are therefore spoiler-proof, let's have a look at the concluding part of a story that, quite apart from the exciting tale of imprisonment and betrayal on Skaro, offers fresh revelations about Davros's eyes and the Master/Missy's children.

Here are a few explanatory notes on some of the references in the story:

Missy refers to the Doctor as a "swot," which is a very British item of schoolyard slang. It refers to a Hermione Granger kind of nerd, the sort who is unabashed about their own zeal for learning. Unlike nerd, swot has yet to be reclaimed as a positive term. Although, the first time we meet the Master (in "Terror of the Autons") he points out to the Third Doctor that his cosmic science degree results were actually higher. So who's the swot now?

On a similar note, "I love killing cleverclogs, they make the best faces" could be a reference to anyone from Osgood in "Death in Heaven" to Chantho in "Utopia" to the entire population of Logopolis, a species that had developed a very advanced form of mathematics. The Master clearly has some unresolved issues from his school days.

That long submarine ride to go and get the TARDIS from the wrong pole at the end of "Cold War" clearly prompted the Doctor to update his Hostile Action Displacement System, the one the Second Doctor introduced in "The Krotons." It is now a dispersal system, which must be far more convenient.

The scenes on Skaro were filmed on the slopes of Mount Teide, Tenerife, which—very fittingly, given the explosive events that take place within the Dalek sewers—is an active volcano.

Both the Doctor and Missy prefer their beverages to be served in a cup and saucer. As we've seen in the clip above, Missy likes café con leche, whereas the Doctor prefers tea and appears to be able to produce the means to make it, and the crockery to enjoy it, at a moment's notice.

This isn't the first time the Doctor and the Master have worked together to overcome a shared foe. Previous fragile alliances have occurred in "The Claws of Axos," "The Five Doctors," and "The End of Time."

Whether this is truly the end of the sonic screwdriver or not, the Doctor's new sunglasses are the latest in a long line of sonic devices he has come across in his travels.

Sarah Jane Smith had sonic lipstick in "Journey's End;" Captain Jack Harkness had a sonic blaster in "The Empty Child;" Nyssa destroyed a Terileptil android with a sonic booster in "The Visitation" (ironically the same story in which the Doctor's screwdriver was first destroyed); the Sixth Doctor used a sonic lance in "Attack of the Cybermen;" the Sea Devils used sonic discs as a kind of ray gun in "The Sea Devils" and their cousins the Silurians used sonic lanterns to herd dinosaurs in "Deep Breath;" the Scaroth planned to use a sonic knife to cut the glass around the Mona Lisa in "City of Death;" the Eleventh Doctor had a sonic cane in "Let's Kill Hitler" and Matron Cofelia had a sonic pen in "Partners in Crime." Oh and the Ice Warriors used sonic cannons.

The synthetic pulse of a Dalek "heartbeat" makes a welcome return, having made its first appearance in the very first Dalek story. It has been used in some of the most notable Dalek epics over the years—from "Destiny of the Daleks" to "Victory of the Daleks" and accompanies the Dalek eyestalk in this Season Eight trailer:

https://www.youtube.com/watch?v=TivqZTq5u6Y

Missy's relationship with the Daleks has always been a tricky one. They may have been partners in "Frontier in Space," but one of his previous incarnations was executed by the space rotters at the beginning of the 1996 Doctor Who TV movie. Not that this will stop Missy from forging an alliance if the chips are down. Clara's relationship is similarly odd, given that part of her that had been fractured off into in the Doctor's timestream was once Oswin Oswald, a human converted into a Dalek in "Asylum of the Daleks."

And finally: "anyone for dodgems?" uses the British term for fairground bumper cars.

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