Checking in with Rory and Amy, The Doctor reports that he still hasn't tracked down their daughter, though he is quick to point out that - logically - they know he IS going to do it eventually. Joining them unexpectedly is their old friend Mels, an dodgy sort who is driving a car that she admits isn't hers... just before the sound of sirens can be heard in the background. Fully aware of who The Doctor is (though he has no idea who she is), she pulls a gun, motions everyone into the TARDIS and suggests they go kill Hitler.
The party arrives in Germany circa 1938... just in time to save Hitler's life from a most unusual assassin. Nobody is particularly happy about this, even before Mels is accidentally shot by Hitler, starts to regenerate and then tries to kill The Doctor...
THE GOOD PARTS
* Moffat is a great idea man and is very good at developing those ideas in a brief span of time. One such idea is the assassin who comes after Hitler - a group of miniaturized people piloting a human-sized, shape-shifting mecha, traveling around time seeking out the most vicious villains in history in order to make them experience all the pain they ever caused others just before they died. That concept alone would be a wonderful story by itself, never mind being one aspect of a bigger story. And that is why we love Doctor Who so much.
* Mels' real identity isn't much of a shock but what comes after IS rather surprising.
* The scene in which The Doctor screams while being confronted with images of all the Tenth Doctor companions whose lives he screwed up is magical. Matt Smith nails the core of The Doctor in that moment, as we can see that the pain of the poison in his system hurts but being reminded of his past mistakes hurts more.
* Who would have thought that you could turn the phrase "You will die in 32 minutes." into a hilarious running gag?
* There are a few minor logical plot holes. It seems rather unlikely, for instance, that our time-traveling assassins would get so far as they did in infiltrating Hitler's offices only to just then realize they had come too early as they're about to torture him. This is the sort of thing you'd expect a bunch of experienced time-travelers to research well in advance. Also, why in the name of all that is good-and-plenty is the TARDIS able to crash through the wall of Hitler's office without anyone coming to investigate? You'd expect there to be two-dozen storm-troopers coming through the door in less than a minute!
* I suppose if you can steal from anyone you can steal from yourself. Still, I can't believe that Moffat wrote in the "Well, I KNEW that you knew..." scene as The Doctor and River try to one-up one another during their Mexican stand-off, mirroring the similar scene between The Doctor and The Master in Moffat's Doctor Who parody story Curse Of The Fatal Death.
THE FINAL VERDICT
A solid episode that, thankfully, has little to do with its' attention-grabbing title. Moffat manages to surprise us with the promise of one of the many important historical figures never directly dealt with in the show before only to ignore it completely in favor of a chaotic but enjoyable character piece.