Broadly, this is little more than a remake of Doctor Who and the Silurians, with human activities underground inadvertently awakening a dormant group of Silurians, who decide they want the planet back. We get the same sort of infighting among the Silurian factions, and the problem is ultimately solved by sealing the tunnels back up. But where it differs is in the emphasis, and in some of the human characters. The biggest difference is probably represented by the character of Ambrose, who's terrified at the thought of losing her grandfather after having lost her husband and son to these strange creatures. She's a desperate woman, and as a result she is, as the Doctor puts it, "so much less than the best of humanity". Her actions, however, are carefully calculated so as not to appear ruthless or (sorry) cold-blooded, but rather as a situation that escalated too quickly and went terribly wrong in the death of Alaya (who, let's be honest, was probably looking for an excuse to be a martyr and thus provoke a war), and which she now has to try and make the best of. It's not pleasant or comfortable, and I doubt anyone watching is on Ambrose's side, but you can see how she got to this point.
The Doctor asks the representatives of the Silurians and humanity to negotiate a peace. ("Cold Blood") ©BBC |
So it's not a letdown, and as far as remakes go it does manage to provide some interesting new elements to make this story seem not wholly derivative (and it's streets ahead of the other remake this series, "Victory of the Daleks"). It also introduces the Silurians into the modern era, even if no one else to date has taken them up on this (save for the character of Madame Vastra, who pops up periodically after this). For anyone who hadn't seen the stories this is based on, this likely had some interesting twists and turns along the way, and the revelation that there were dinosaur people on the planet before humanity evolved may have been intriguing to those viewers. But for those who had, there's a sense of inevitability about the proceedings, and we never really believe the Doctor's claim that "this is an opportunity. A temporal tipping point. Whatever happens today, will change future events, create its own timeline, its own reality. The future pivots around you, here, now."
It's perhaps not surprising then that this episode will likely be best remembered as the one where they killed Rory again, but this time for good (it seemed at the time), and then erased him from history just to add insult to the injury. It's a testament to Arthur Darvill's performance that even after only five episodes people were upset by his death. It's these contributions to the overarching plot of series 5 that "Cold Blood" in particular tends to be remembered for, rather than for the Silurian plot that took up the previous forty minutes. That right there sums this episode up better than anything else.