The Power of Three (TV story)

 was the fourth episode of the seventh series of Doctor Who produced by BBC Wales.

Synopsis
There have been many ways to invade the Earth, and the Doctor has seen them all – or so he always thought. And then the human race wakes up one morning and discovers the world has been overrun by… small black cubes. Which then proceed to… do nothing at all. A plan is afoot, humanity is endangered – but by what and how and, above all, when?

For the first time in his world-saving career the Doctor has to call upon one of the least of his virtues: patience. And the Ponds face something possibly more terrifying than any world-ending apocalypse: the Doctor is moving in!

Plot
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Cast

 * The Doctor - Matt Smith
 * Amy Pond - Karen Gillan
 * Rory Williams - Arthur Darvill
 * Brian Williams - Mark Williams
 * Kate Stewart - Jemma Redgrave
 * Shakri - Steven Berkoff
 * Ranjit - Selva Rasalingam
 * Laura - Alice O'Connell
 * Arnold Underwood - Peter Cartwright
 * Orderly 1 - David Beck
 * Orderly 2 - Daniel Beck
 * UNIT Researcher - David Hartley

Uncredited cast

 * Brian Cox - Himself
 * Lord Sugar - Himself

Story notes
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Ratings
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Filming locations
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Production errors
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Continuity

 * Rory's father Brian reappears. (TV: Dinosaurs on a Spaceship)
 * The Eleventh Doctor, Amy and Rory have fish custard. (TV: The Eleventh Hour)
 * Kate Stewart is the daughter of Brigadier Alistair Gordon Lethbridge-Stewart. She previously appeared on-screen in HOMEVID: Downtime. She shortened her family name when she joined UNIT as she wanted to be judged on her own merits. Her appearance marks the first time that a character introduced in a direct-to-video spin-off reappeared in the television series.
 * Ten years have passed since the events of The Eleventh Hour in Amy's personal timeline.
 * The Doctor, talking to a flying cube, says "Is that all you can do? Hover? I'd a metal dog that could do that" referring to K9 Mark IV (and possibly to K9 Mark 2).
 * The Doctor once again asks how humans cope with just one heart. (TV: The Shakespeare Code)
 * The Zygons are mentioned. (TV: Terror of the Zygons)
 * Twitter is mentioned again. (TV: The Girl Who Waited)
 * The UNIT base beneath the Tower of London is visited. It was previously mentioned in The Christmas Invasion and The Sontaran Stratagem.
 * King Henry VIII is mentioned again (and partially seen.) (TV: A Town Called Mercy)
 * The Ponds' anniversary takes place. They previously got married in The Big Bang.
 * A wormhole was last seen in Planet of the Dead.
 * A voice interface was last seen in Let's Kill Hitler.
 * Artron energy is mentioned. (TV: Death of the Doctor (TV story))
 * Rory kisses the Doctor on the cheek. The Doctor kissed Rory on the mouth in Dinosaurs on a Spaceship (TV story).

DVD releases
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Blu-ray releases
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