This has been one intriguing episode of Doctor Who to say the least.  Unlike the previous two episodes, Dr. River Song is no longer with them as she put herself back in prison in the future. Amy Pond and Rory are still within him, and through an interstellar distress message by a deceased Time Lord, it lured the Doctor onto a dark asteroid inside a Bubble Universe, a separate, micro-universe.  In a way, it’s similar to the parallel plane that Rose Tyler, her parents and the human Doctor (former Doctor Who David Tennant) are trapped in currently.

(On a side note, with the The Big Bang 2 episode [season 5, episode 13] of this current Doctor Who season, although it sealed off the cracks across time and space, those who are separated like Rose and those trapped in the alternate parallel universe still have knowledge of the Doctor.  However, Martha Jones, Donna Noble, Wilfred Mott, Mickey Smith and others will have their knowledge of the Doctor since the Big Bang 2 essentially realigned their timeline. However, there remains two caveats.  All the former companions and others can remember the present Doctor, but they have to want to remember the Doctor  similar to Amy Pond and Rory. The second caveat is that time agent Jack Harkness of Torchwood remains free since he is a time agent after all where changes in the timeline have little or no impact on him directly.  A final note concerning the Ood, Nephew, in thi episode did not acknowledge the existence of the present Doctor since I believe that he or his species have knowledge thereof  for the same reason as Donna Noble and Martha Jones.)

I believe this is the first time that the Doctor met his TARDIS incarnated in Idris.  It was a brilliant episode as she called herself Sexy, after he repeatedly in many episodes before as a “sexy thing.”  In this episode, after rebuilding a makeshift TARDIS to enter his blue police box, she stopped House, spoken by the brilliant Michael Sheen, from entering the present Universe.  This episode was fantastic as the current Doctor learned about his TARDIS emotionally.  She gets to where he needs to go, not where he wants to go.  This will be critical later on this season and afterwards.  The Doctor now appreciates his TARDIS more now.

The final twist this episode was the death of former Time Lords by House.  In other words, Daleks aren’t the only enemies capable of eliminating Time Lords, and this could pose problems for the present Doctor later on.  With more external threats this season, the Doctor, Amy and Rory may be facing more difficulties than ever before.  As much trouble that Rose Tyler was in previous seasons, Amy and Rory may be in extremely hostile situations.

This season has been one of the best so far, as the adventures have gotten more intense, emotional and psychological.  These episodes have been getting darker — and with the last one, very green as well.  Upcoming, we have two more episodes left before a hiatus prior to completion of the current season.  It will be interesting to see where the Doctor goes next and onward.