Doctor Who-Let's Kill Hitler

                                                Following their escape from Demon's Run Amy and Rory drive through a corn field to meet back up with the doctor after creating a crop circle to try to get his attention. Almost immediately a red Corvette stingray pulls up,and a woman emerges carrying a pistol and holds up the doctor. Her name is Mels,an old friend of Amy and Rory's whose known them since childhood and has always known a particular fascination with the doctor and time travel.  Her intention is to steal the TARDIS and "kill Hitler". Almost destroying the TARDIS in the process,by the time they arrive in 1938 Berlin,they begin by imprisoning the puzzled Furer himself in a closet as Mels "regenerates" into River Song after being shot at by a robotic version of Nazi Erich Zimmerman,whose reason for trying to intercept Mels is now abundantly clear to the doctor. It was in fact River Song,who still knows of herself primarily as Melody Pond,who will be the instrument of his death in Utah. 

                                  During her regeneration crisis,Melody/River goes on the lamb. She manages to confuse Nazi troops and even crash a formal reception where she steals the the guests clothes. Meanwhile Amy and Rory become miniaturized into a disguised robotic version of Amy. The doctor for his part his bigger problems. When Melody/River kissed him after she regenerated,she ejected a lethal poison into him. As he struggles with his last half hour of life Amy and Rory find themselves inside the dimensionally transcendental,TARDIS like Teselecta,used by a temporal control agency attempting to apprehend Melody/River for her future crimes. Par the doctors instructions Amy and Rory are able to use their identity matches to fool out the Teselecta into escaping. As the doctor let Melody know via the robot that she'd one day be River Song,she gave her last regenerations to the doctor to save his life. As she awoke in a future medical facility the doctor,Amy and Rory leave her to her devices. By the 50'th century however,Melody is applying to be an archaeologist.

                                 During much of series five and so far into series six,the doctor was becoming more and more aware of the origins of River Song's place in his life. He started to see the conflicts between free will and a hidden biological imparitive within her even as far back as her revelation of being a murderer when they met with the Weeping Angels. So as it were,Melody's "regeneration" in 1930's Berlin represented the doctors first encounter with River Song,as well as their obviously paradoxical relationship in time and space. This episode has over a dozen plot lines,all moving at an extremely fast pace. There's River's "fear and loathing"-like regeneration delirium,mingled with her programming to kill the doctor. There's also the concept hinted at in the manner in which Amy and Rory escaped from the Teselecta that could very well point to how the war with the doctor might've started in the first place: his intent on protecting River Song even at the cost of his own life.  There relationship,though itself even emotionally paradoxical is the key element to this episode it's a big hoot to watch. And there's a whole lot more here than even that.