Despite the attention grabbing title, ‘Let’s Kill Hitler’ isn’t really about Hitler, or indeed killing him. In fact, this episode is actually about River Song (Alex Kingston) at the earliest chapter of her life.

The story begins with an exciting pre-credit scene involving The Ponds (Karen Gillan and Arthur Darvill), a Mini and a crop field. Amy and Rory have been trying to locate the Doctor to see if he’s made any progress finding their baby following her kidnapping in A Good Man Goes to War. But as anyone who watched the Let’s Kill Hitler prequel will know, the Doctor doesn’t answer his phone.

Needless to say, the TARDIS trio are reunited quickly enough and we are introduced to new bad girl, Mels, played by Nina Toussaint-White. Via a lovely flashback sequence, we learn that she was good friends with Amelia (Caitlin Blackwood) and Rory (Ezekiel Wigglesworth) from a young age and throughout their life as they grew up.

After Mels’ flirty introduction, the episode quickly ramps up with the TARDIS crash landing in Hitler’s office in Berlin on the eve of war. Here is where the main story begins. Hitler has been targeted by The Teselecta, a robot controlled by mini-people that can shift into any human form (with a transformation that echos Terminator 2’s T-1000). The Teselecta wants Hitler to pay for his crimes to humanity, but the Doctor inadvertently ends up saving his life.

From here on Hitler is quickly discarded in a humorous scene with Rory. To talk about the plot beyond this would spoil the episode. But we can say that are a lot of exciting moments; the Doctor thwarting multiple attempts on his life with cunning that would make Sherlock proud; the ‘return’ of past companions and fish fingers and custard; the Antibodies with their joyously silly dialogue, “Remain calm as your life is extracted,” “You will experience a tingling sensation and then death.”

As previously stated though, this is River Song’s episode and Alex Kingston pretty much steals any scene she is in, with another unforgettable entrance, or three. She also gets the best line of the episode whilst dealing with some Nazis. However, Matt Smith gets to do some fine work as he wrestles with guilt and faces the end of his life. Karen Gillan and Arthur Darvill get to explore parenthood in the weirdest way possible.

Let’s Kill Hitler does provide a few answers to some long burning questions. You learn how River can fly the TARDIS and who taught her; more about the regeneration at the conclusion of Day of the Moon , the Doctor’s death; The Silence and the meaning of “Silence will Fall.” But be warned, in most cases answers come with more questions and perhaps the oldest question of them all…

The 48-minute run time moves along at a brisk pace and it feels like a few ideas could have benefitted from more time. The plot potential of killing one of the nastiest men in human history does end up taking a backseat as soon as River comes along. But, all in all, this is a fantastic episode to kick off the return of Doctor Who’s sixth series. Funny, thrilling and full of the twists and turns you’ve come to expect from Steven Moffat. Just don’t expect all the answers just yet.