Blink was the 9th episode of the third series of the revival of Doctor Who, written by Steven Moffat and starring David Tennant as the 10th Doctor and Freema Aygeman as his companion, Martha Jones. Besides they are the stars in name only: due to a tight production schedule, "Blink" was filmed with the one-off characters being the stars, and The Doctor and his companion being relegated to a cameo appearance in their own show.

The plot of the story follows Sally Sparrow, a young woman who is investigating a deserted house, and finds people around her disappearing. At the same time as this is happening, she is getting strange messages around her: writing on the wall of the house, addressed to her, beneath the wallpaper, a weird series of messages as an easter egg in DVDs. These messages all come from a man known as The Doctor, although what they are saying is hard to piece out. Although it seems to involve the Weeping Angels, statues that can only move when they aren't being observed. Stare at a Weeping Angel, and you have nothing to fear, but the moment you blink, it can move "faster than you can imagine". Using some clever thinking, and teamwork that works across decades, The Doctor and Sally Sparrow (together with her friend Lawrence Nightingale) manage to trick the Weeping Angels' with their one weakness, and everyone lives, at least until the crash of the Byzantium.

This episode is considered to be one of the iconic and best of the show since 2005, and while many people have pointed out various reasons why, I think I have the best answer: Doctor Who is a show about many things, and this show hits the entire spectrum. Strangely enough, a bottle episode written and filmed to save on the budget of the series is perhaps the best summary of what the show is about.

  • Time Travel: It has been remarked that while time travel provides neat plots and costumes for the show, Steven Moffat was one of the first writers who used time travel as integral to the plot. In "Blink", characters move through time, communicating with each other in an odd assortment of ways that lead to paradox. Which leads us to:
  • The Doctor and his eccentric, dopey genius. In trying to explain the nature of the temporal paradoxes, the Doctor eventually ends up at a loss for words, leading to the iconic explanation that time is a ball of "timey-wimey, wibbly-wobbley...stuff". He also gets to show off both his genius and goofiness in building a "Timey-Wimey detector" that "Goes 'Ding' when theirs stuff". The Doctor doesn't get much screen time, but what he has is golden.
  • Horror: Doctor Who is a Science-Fiction show with horror elements, and the monsters in this story, the Weeping Angels, are very frightening, and based on a simple concept: they only move when you aren't looking. Although the episode is totally bloodless, and the Angels are just stone people with sharp teeth, they still manage to be very frightening, only to be superseded with the introduction of The Silence.
  • Pathos: Sally Sparrow meets a man who is then sent back in time, and must live for decades until he meets her later, on his death bed. For her, the two incidents are a few hours apart. For him, decades. He meets her and comments that when they first met, it was raining, and she answers: "It's the same rain". What could be a simple time-travel gimmick is used for great emotional effect.
  • Romance: The aforementioned interaction, as well as Sally's interactions with Lawrence Nightingale, are sweetly romantic.

And all of this takes place within about 45 minutes: humor, terror, romance, and drama, as well as some old-fashioned science-fiction weirdness. And none of it seems out of place or rushed. All in an episode that, in part, was just designed to fill out a tight production schedule. This is also interesting because the writer, Steven Moffat was later made the head writer of Doctor Who. opinions of his over-the-top time-spanning adventures have been mixed, with some people feel it is rushed and lacking in characterization, while others think it is an ambitious attempt to use the full potential of the show's concept. I feel that both of these are true, and I somewhat wonder why the Steven Moffat who could fit all of Doctor Who into 45 minutes seemed to have problems with doing the same thing in 26 episodes.