The episode's early sense of fun is of course merely intended to lull us gullible viewers into a false sense of security. Seven minutes in, a nation's collective jaw dropped as The Doctor - this show's lead - is mercilessly gunned down. This plot twist is simply stunning, and it's difficult to imagine even casual viewers not sitting up to pay attention at this point. On a purely parental note though, while scares for the kiddies are all well and good, it's perhaps questionable how traumatic it could be for a young child to see their hero shot to death and subsequently burnt up.
With the series arc firmly established, the plot for this two-parter really kicks into gear. This first episode has a strong American feel, emphasised not only by the filming in Utah, but also by the ensemble lead cast and the presence of guest star Mark Sheppard, a veteran of cult shows such as Battlestar Galactica and Supernatural. The gravel-voiced actor takes on a rare heroic role here and is predictably brilliant as former FBI operative Canton Everett Delaware. The episode's other major guest star Stuart Milligan also turns in a solid performance as Richard Nixon and avoids making the President a blustering cliché. He is however slightly hampered by facial prosthetics that perhaps stray a little too far into the realm of cartoonish exaggeration.
As the Tardis team and Canton hunt the source of Nixon's recent phone calls, the episode's frantic pace slows a little, allowing for some nice character moments. River and Amy's discussion regarding the flexibility of time is certainly intriguing and, with The Doctor's fate in the balance, a definitive answer to the question 'Can time be rewritten?' seems like it could finally be on its way. It was an interesting decision to pair off Rory and River in these final scenes, but it works brilliantly. The two characters bring out the best in each other, as we finally see past River's bravado and get a glimpse of the broken heart beneath, while Rory silently broods over the state of his own marriage.
All in all, this is a fantastic launch for the sixth series of Doctor Who. The only obvious criticism is that this instalment and the one that follows could prove too confusing and too frightening for kids, but perhaps we're just underestimating the show's young fans? Time will tell, as it always does, but ultimately the fact that a show that's been running on-and-off for almost 50 years can still subvert expectations, and produce something as simultaneously shocking and thrilling as 'The Impossible Astronaut', is something for the Who team to be proud of.