The Doctor returns to Earth to discover that black cubes have appeared all over the planet, mystifying the entire world: is it an alien attack or some kind of viral marketing ploy? When the cubes show no sign of activity, the Doctor decides to move in with Amy and Rory to observe the cubes over time. The cubes’ inactivity – and his own – drives the Doctor to distraction. Even when Rory’s dad Brian pitches in to observe the cubes, the cubes do nothing. The Doctor is surprised when UNIT arrives to question him, led by Kate Stewart – Brigadier Lethbridge-Stewart’s daughter. When they do awaken, the cubes’ behavior ranges from benign to deadly to baffling, and the attention of the entire human race is riveted – which is exactly what the mind behind the cubes wants. The slow invasion of Earth is about to speed up, and even the Doctor can’t stop it.
written by Chris Chibnall
directed by Douglas MacKinnon
music by Murray GoldCast: Matt Smith (The Doctor), Karen Gillan (Amy Pond), Arthur Darvill (Rory Williams), Mark Williams (Brian Williams), Jemma Redgrave (Kate Stewart), Steven Berkoff (Shakri), Selva Rasalingam (Ranjit), Alice O’Connell (Laura), Peter Cartwright (Arnold Underwood), David Beck (Orderly 1), Daniel Beck (Orderly 2), David Hartley (UNIT Researcher), Professor Brian Cox (himself)
Notes: The character of Kate Stewart was established in the 1995 direct-to-video spinoff Downtime, on which occasion she was played by Beverley Cressman. At that point, Kate showed no interest in UNIT, though obviously her priorities changed, perhaps as a result of UNIT’s intervention in the Yeti incursion at NeWorld University in that story. (It’s entirely possible that the two iterations of Kate Stewart weren’t meant to be the same person, but for those who like a wider Doctor Who universe, nothing in either this episode or Downtime directly contradicts the other story.) It is strongly implied that Kate has reformed UNIT somewhat (previous Doctor Who and Torchwood episodes had depicted UNIT becoming more ruthlessly militaristic).
Original title: Cubed
LogBook entry & review by Earl Green
Review: A surprisingly gripping episode of an unconventional invasion scheme, The Power Of Three was the victim of a somewhat misfired promotional build-up that implied the whole episode would be about the Doctor going stir crazy while hanging out with Amy and Rory; there’s a lot more to it than that. One of the best things The Power Of Three has going for it is a repeat engagement with Brian, who may be the best ancillary character that the Moffat era has given us since Craig and Sophie. (My TARDIS dream team would be Brian and Wilf. Would you even 
need other companions with those two around?) One of the biggest drawbacks to the exit of Rory and Amy is that there’s no reason for Brian to appear again afterward.
Doctor Who has done “slow invasions” before, just not intentionally. (The Invasion, the first UNIT story, was also a slow invasion, mainly by virtue of being spread out over eight episodes.) This one is mercifully compact, but it still works, and the cunning plan behind it is a smart one with a worthy adversary. Much of the reason behind the time spent with Rory and Amy is, naturally, part of the build-up to their impending (and heavily hyped) exit, but The Power Of Three works even without that knowledge.
The character of Kate Stewart is an inspired invention, helping to steer UNIT back into a more scientific/intelligence organization after the Russell T. Davies era repainted UNIT in shades of the U.S. Department of Homeland Security. (Re-steering UNIT toward its roots is a welcome development in itself; the only thing sadly missing from all this would have been a handoff episode, though the sad death of Nicholas Courtney obviously precludes that from ever happening.)
The Power Of Three is the best of the 2012 episodes, and stands up to repeat viewing.