‘Hello sweetie.’ The final River Song episode parks all the complicated timey-wimey flowchart stuff, the Inception elements of Last Christmas and even the Christmas Carol pastiche to tell perhaps Moffat’s simplest and most direct story. River Song’s nearly-full diary makes the point that, like Hell Bent, it’s about endings. Unlike Hell Bent, it doesn’t rage against them: ‘Times end, River, because they have to.’ There’s a sense of completion and closure, and, if not quite ‘happily ever after’, that the Doctor and River have found contentment together (with the final joke that their last night will last 24 years).

This wistful love story is wrapped inside a sitcom about a tyrannical giant robot and a jewel heist, with three TV comedy stars milking the material for all its worth. Greg Davies and Matt Lucas are very funny, but Capaldi is on fire. There are some token nods to his audible frowning and cross arms, but this is the 12^th Doctor enjoying himself, having fun pretending to be astounded by the TARDIS’ impossible dimensions, gurning jealously as River snogs her many husbands, making her laugh at Hydroflax’s head bag, and generally milking the fact that, for once, he knows River (and the TARDIS) better than she knows him – even if he somewhat disapproves of what she seems to be like when he’s not there. Alex Kingston responds to a script that no longer requires her to be the mysterious older woman with a performance of great warmth and wit, making me wish we’d seen more of River in this mode.

I appreciated how far Capaldi’s come since Deep Breath in the parallel scene of him and his companion in a restaurant surrounded by enemies. Here, he confirms rather than confounds the faith his companion has in him. The climax on the Harmony & Redemption is a little bit hand-wavy, largely because Moffat hasn’t written in the usual twist (unless you count River having read that the ship is going to crash – in which case surely she shouldn’t be surprised it’s going to hit Darillium), but the last scenes at the restaurant by the singing towers are a beautiful, elegant end to River’s story. I’ve never loved her or the 12^th Doctor more than here. This might not be Moffat’s cleverest script, but I think it’s his most sophisticated.

Next Time: Friend from the Future