[WARNING: The Following Review Contains SPOILERS!]

River Song has a rather special relationship with The Doctor. The first time he met her was the last time she met him, but The Doctor trusted her immediately because she knew his real name and possessed a sonic screwdriver. He met her many times over the centuries, slowly learning more of who she was, as she – from his perspective – grew to know less and less about him.

Eventually, The Doctor learned the truth of River Song’s origins – that she was kidnapped as a baby to be turned into a weapon against him. But her captors didn’t think that baby girls grow into teenage girls and teenage girls rebel. And what better way to rebel as an assassin than to fall in love with the man you were raised to destroy?

The two married, after a fashion. And they passed the point where The Doctor knew he would see River for the last time. At least, that’s what The Doctor thought… before he answered a call for a surgeon and was surprised to find River Song waiting.

The Doctor was even more surprised when River did not recognize him, despite having always recognized him no matter what face he wore in the past. And there is no word to describe the level of surprise that The Doctor experiences when he learns just what River Song gets up to when he isn’t around. Such as getting married to at least two other men, becoming a queen and trying to steal the most valuable diamond in the universe.

Showrunner Steven Moffat said that he went into this episode thinking it might be the last Doctor Who story he’d ever write. Ultimately, he did decide to return for another series, but The Husbands of River Song would have been a wonderful way for Moffat to end his tenure. As it is, the episode is an excellent capstone for the outstanding Ninth Series of Doctor Who.

River Song has long been a divisive figure among Whovians. I dare say that most love the cheeky professor, gloriously brought to life by Alex Kingston, but that some of the stories she’s starred in have involved Steven Moffat’s worst writing.  It would be fair to say that Moffat has a tendency to create female protagonists who are intended to be a mystery of sorts for The Doctor to solve and that while this has led to some of the best Doctor Who stories of all time (The Girl in the Fireplace, The Snowmen and even Blink if you consider it from The Doctor’s prespective) it has also led to some less then stellar episodes, where River was more of a gimmick than a character.

Thankfully, The Husbands of River Song is Moffat at his best. And we are finally given the farewell that the character of River Song – and Alex Kingston as an actress – deserved to get years ago. Despite this being a worthy send-off, I’m sad to see the character go because the chemistry between Peter Capaldi’s Doctor and Alex Kingston is much stronger than it ever was between Kingston and Matt Smith. And Capaldi is clearly having fun overplaying his part as the oblivious companion, going on about how it’s bigger on the inside as River steals his TARDIS and suggests this is not the first time she’s taken “Sexy” for a ride without him knowing about it.

I’d love to see more of Capaldi and Kingston together in the future, though that’s technically impossible.  Still, as The Doctor notes, one last night can last for years with a Time Lord. Might we see what the two get up to during their last night in a Big Finish audio play in the future?

Spoilers, sweetie…