Continuing Doctor Who - the Doctor, Amy, Rory, and Amy and Rory's best friend Mels who was never mentioned before are going back in time to kill Hitler!
Though if that's the case, then her entire existence is a time paradox since she caused Amy and Rory to get together in the first place, leading to her own birth.
Given what I know about Rasputin in Dr. Who, I find it funny that these aliens impersonated the Master. (Either that, or Rasputin was really unlucky and got impersonated twice)
It's bizarre to establish that someone with the Doctor (presumably Mels, since they say "it's her") is considered in-universe to be a bigger war criminal than Hitler.
So Time Lords can control their regeneration to some extent? (River made a comment on focusing on her dress size - I assume the Doctor just goes with "random")
Thinking about it, I like how they're taking the time to set up how the Doctor survives rather than it being a Deus Ex Machina - the Doctor knows when, where, and how he dies, he has access to a time machine (and he's 200 years older when he dies, unless he was lying), and this season has introduced multiple ways to copy yourself.
Going by the Doctor's reaction, he's giving them false hope that Amy and Future Amy can both survive. (He shook his head no when Future Amy wanted to be brought along too, despite giving some technobabble and claiming it was possible)
Watching an interview with Lalla Ward on the 4th Doctor's box set, and they had some fun when she's talking about filming with blue screens where they can put all sorts of things behind you.
...they're probably not going to kill Hitler.
Next episode looks like it's inspired by The Shining, with some Weeping Angels thrown in for good measure.