Doctor Who: Every Modern Companion's DEFINITIVE Episode

River Song is an incredible character, but in almost every story she appears in, she's defined by everything around her. She's Moffat's great enigma.

For most of Matt Smith's run, the Doctor (like he is with Clara) seems mostly attracted to her because she's a puzzle to be solved. There are teases and spoilers and paradoxes, the reveal of who she is and why she's in jail, her wedding to the Doctor... ultimately, she's a plot device. Luckily, Alex Kingston plays her with such charm that this is easily overlooked.

The Husbands of River Song, casting off the shackles of the Smith era's timey-wimey series arcs, is a story that finally treats River as a person. The episode isn't about who River is in relation to the wider Doctor Who mythos, and it doesn't present any big mysteries. It's just about her, what the Doctor means to her, and what she means to him.

To be more specific, the story is about what it actually means to love the Doctor. The Smith era presents them as being a couple but you never quite buy that Eleven loves River. Here, she pours her heart out in a beautiful monologue, and in that moment, it's the first time you can really see that he loves her too.

There's no clutter in this story – there's no full-time companion to be juggled and the threat is relatively minor and lighthearted, which befits both Christmas and the rom-com vibes the episode is shooting for. River, for the very first time, is a co-lead (and Kingston finally gets her well-deserved place in the opening credits).

The story gives us payoffs that have been teased as far back as River's first appearance in Silence in the Library, and they land precisely because they have been built towards for so long. The Singing Towers of Darillium and the Doctor gifting River her screwdriver are woven into the narrative in a more beautiful way than we might have imagined, culminating in the wonderful reveal that their final date night lasts not a few hours, but 24 years.

Alex Kingston puts in her best performance here, unburdened by having to play the mysterious angle. She's able to play River with a looseness and vulnerability that there wasn't space for before, and her chemistry with Peter Capaldi is electric.

The choice to make this episode a quiet, personal story that patches what was most lacking in River's character was an inspired choice that ended Kingston's time on the show on a soaring high.