"A Time Lord victorious."

You had a chance to read my advance review of the sensational Doctor Who: The Waters of Mars but now that the latest David Tennant-led Doctor Who special has aired, I'm curious to see just what you thought of the special, written by Russell T. Davies and Phil Ford, which found the Doctor grappling with some weighty issues about predetermination, free will, and responsibility.

As I said in my review, I thought that Doctor Who: The Waters of Mars was the darkest and most adult of the 2008-09 Doctor Who specials and brought us a Tenth Doctor for whom time was running out, both literally and figuratively. The Tenth Doctor's song is ending (and with it, rather sadly, David Tennant's run on the series) and he's waiting to hear those four knocks that will signal his doom but before then the Doctor made a stunning decision that might seal his fate once and for all.

In choosing to intervene in the "fixed time" element of the Bowie Base One disaster, the Doctor oversteps his bounds, both as hero and as the last of the Time Lords. Throughout the series' run, the Doctor has been wary of interfering with events or times that are fixed. His involvement in Pompeii ended up bringing about the city's destruction as a result; Pompeii had to be destroyed and the Doctor had always been the one to destroy it. At the time, it was a tough decision to make but one that he had to do in order to save the human race from a greater evil. Perhaps the ability to make those moral judgments--to safeguard the greater good--is both the Doctor's strength and his curse.

Here, he's faced once again with an enormous dilemma but there's no companion to push him towards the correct course (as Donna Noble had done in Pompeii). As before, he saves a handful of people from certain doom but in doing so, alters the natural course of the universe. While Donna's insistence that they save one family doesn't have any huge implications about the future, the Doctor's interference here does. Adelaide Brooke's death on Bowie Base One directly influences her granddaughter, who follows in Adelaide's footsteps and takes the human race to the stars.

The Doctor, in an act of hubris, decides not to follow time's natural path. He opts instead to save Adelaide Brooke (Lindsay Duncan), believing that she can still inspire her granddaughter and still save the human race. The Doctor wrongly believes that he is not chained to the laws of time and space. He is the last of the Time Lords and time itself bows to his command. He saves Adelaide, aware of the costs. It's a monumental error, perhaps made because he knows his own death is stalking him, circling him and ready to pounce. If he can save Adelaide, perhaps he can save himself?

But it's a dark gift that is too much for Adelaide to bear, too much responsibility for one person to carry. She knows that the fate of the human race rests on her slender shoulders and, even if the Doctor will not make the right decision, she will. She sadly enters her house after telling the Doctor that a "Time Lord victorious is wrong." And she promptly kills herself, righting the course of history and keeping the human race on the path they were meant to be on.

It's a rare miscalculation from the usually infallible Doctor, an act of shocking hubris that comes as a surprise but also perhaps serves as a fitting consequence of the death and destruction he's left in his wake these past few years. A fatal flaw that points to his inevitable regeneration and the end of this form.

As for the Ood who appears before the Doctor, he is a harbinger of things to come. The darkness is closing in on the Doctor, even as he rallies to try and fight his fate. The fear in his face as he attempts to escape the inescapable (and the sound of danger-alerting cloister bell) is palpable. He'll fight with his very last breath to stay alive and what's even more gut-wrenching is that we, as the audience, knows that he ultimately will fall.

What did you think of Doctor Who: The Waters of Mars? How did it compare to the other specials? Just what will happen to the Doctor in the final two-part episode of David Tennant's run? And how sad are you that Tennant is leaving the series? Discuss.

Doctor Who: The End of Time, Part One airs Saturday at 9 pm ET/PT on BBC America.