The concluding part of the adventure featuring the Flesh (programmable matter) was quite entertaining, until the end, which was staggeringly good.
The gangers and their human counterparts continued to plot one another’s demise, whilst the Doctor and Smith (I think John Smith was a name the Third Doctor sometimes used) tried to confound them and keep everyone alive.
Rory got tricked by Fleshy Jen who, in stark contrast to her sickly sweet human counterpart, was a bloodthirsty lunatic. Rather stupidly, even given his ignorance, he allowed her to trick him into locking the Doctor et al. in a room that would burst with acid. The Doctor and Smith worked together to ensure their freedom, and the gangers and humans ended up both fleeing the twisted monster Jen became.
It’s possible Smith survived his self-sacrifice (he used the sonic screwdriver to dissolve Monster Jen but it destroyed him as well), and that would prove a useful turn of events when it comes to explaining the first episode of the season.
Very much enjoyed the two Doctors collaborating, and the odd reference to the earlier incarnations (especially reverting the polarity of the neutron flow).
However, what made the episode particularly good was the ending. The Doctor had deliberately sought out the Flesh and his knowledge of it was alluded to in the previous episode. I’d thought it might be the forerunner of Time Lord regeneration technology, others have suggested it could be Sontaran cloning technology.
In fact, the truth was that Amy was a ganger. Her real self was pregnant, which explained her strange quantum physics approach to procreation. The creepy eye-patch lady really was a midwife, and a rather horrid one. When the Doctor dissolved the ganger Amy awoke in confinement, about to give birth.
It seems that she’s been a ganger for the entire season, raising the question of when she was taken, how, and by whom.
Very exciting and excellent ending, and we have just one more episode before the mid-season interval of about three months.