While watching any television series, one key factor which keeps me hooked is usually the longer-running story arcs which tie everything together. These certainly play a prominent role in the relaunched Doctor Who as well: Bad Wolf, the Doctor's constant fight against the Daleks, the return of the Master, and then the crack in the universe present throughout the fifth season. It was this arc, especially its conclusion in the episode "The Big Bang", which made me realize that in the case of Doctor Who, it is not the ongoing story which keeps me coming back. Indeed, almost every Doctor Who story, be it the plot of an episode or the overarching theme of a season, follows the same rubric: something fishy is going on, the Doctor finds out what it is, the Doctor and his companions and/or the earth and/or the universe are found to be in an impossibly precarious situation, and then the Doctor finds some impossibly implausible solution which somehow makes everything come right again.
This is nowhere more evident than in "The Big Bang," where the explosion of the Doctor's TARDIS actually destroys the entire universe except for a small portion containing the Doctor and his companions. But hooray--just by remembering things the way they were, Amy Pond is able to bring everything back into existence exactly the way it was. Once the viewer knows that something like this can happen in the Doctor's world, he or she needn't worry about any further predicaments in which the Doctor may find himself. The series' authors will certainly always be able to find more equally impossible ways of saving the Doctor and the universe. This isn't exactly a formula that keeps viewers watching.
After this somewhat sobering realization, I nonetheless continue to watch Doctor Who, albeit with slightly less enthusiasm. What is it that keeps me coming back? I believe that Doctor Who's recurring appeal for me is twofold. First, the Doctor, high and mighty Time Lord though he is, invariably establishes connections with ordinary human beings, and it is in fact these human beings that largely motivate the Doctor to do what he does. Secondly, although the series' viewers discover more and more about the Doctor as time passes, these ordinary humans with whom the Doctor interacts for the most part do not, and it is always entertaining to see how enigmatic the Doctor appears to them; the series' title-inspiring question "Doctor Who?" will never grow old.
No episode encapsulates these two aspects of the series better than "Love and Monsters," which details how a group of people who have had previous contact with the Doctor try to find out more about him and come into contact with him again. The Doctor had helped each one of these people with some problem in his or her past, but then vanished, leaving him or her wondering just who this mysterious doctor really was. The perceived enigmatic nature of the doctor is emphasized by the fact that the entire episode is narrated by Elton Pope, one of the humans searching for the Doctor. Although the Doctor (with the help of Elton) in the end of course saves the day again by vanquishing the evil Abzorbaloff, the memorable part of this episode is how those touched by the Doctor meet up to reminisce and speculate on the Doctor's nature and whereabouts.
"Doctor who?" indeed.