Spoilers lie ahead, as we review the latest episode of the superb Inside No 9…

You presumably know the drill by now. These reviews are billed as filled with spoilers, but in reality, we try to avoid giving away too much in the way of major plot points. That said, however, as always: those who are good at reading between the lines should look away now until after they see how the episode develops.

Nicola (Harriet Walker) and Adrian (Steve Pemberton) have what might be called a good marriage. At least, that’s how it might be framed to anyone visiting their home. They’ve clearly weathered a bad patch – or nine – in their relationship, and when we meet them, it’s obvious that the screaming matches have long since finished, and what is left is exhaustion, sadness, genuine affection – and something else. This episode takes place over what seems to be just under a year, and begins with the couple preparing to renew their wedding vows. Nicola has written a heartfelt declaration of love to her husband, whereas Adrian’s cut and paste job doesn’t even include his own name. Perhaps, as a wedding photographer, he has become used to taking himself out of the picture.

It’s clear that work is important to both of them: Adrian has built a darkroom in the basement, meaning that he hasn’t allowed himself a day off in almost a decade, whereas Harriet has her own, bitter reasons for not going back to the office. There’s a lot left unspoken, things that we, the audience, are required to fill in – much like Adrian’s incomplete jigsaw puzzles – and hint at the couple’s barely contained frustration. ‘I love you,’ Harriet tells Adrian in what turns out in retrospect to be one of the series’ blackest jokes, ‘but you won’t let me in.’ Truth is, Pemberton and Shearsmith have done their job rather too well: the audience is so well trained to suss out how an episode might turn out, it’s occasionally necessary (as in this episode) to throw out a hint towards a surprise ending that never actually transpires.

Inside No 9 has been described by some unimaginative scribblers (like this one) as a modern Tales Of The Unexpected, but in truth individual episodes have been far more sharply original than that. In fact, To Have And To Hold is arguably the first episode that you could suggest a lineage of: there are two particularly nasty short stories, one filmed for television as early as Alfred Hitchcock Presents, that share a couple of narrative links with this one (to say which ones would give away a significant plot point that occurs at the halfway mark – and then another one that happens about four minutes later. But then this has always been one of Inside No 9’s major strengths: not as interested in the twist as much as what happens after the twist.

‘I’ve brought you down to my level,’ Adrian remarks wryly in a scene when husband and wife have managed to set aside the quiet frustration that’s been bubbling under their entire relationship. It’s not that both can’t see the others unhappiness, but each have their own reasons for almost wilful myopia (it’s no accident that both of them need to share the same pair of glasses to see what’s right in front of their face). Money troubles begin to rear up, but Adrian won’t countenance the possibility of change. ‘I won’t make you leave this house,’ he promises his wife. Harriet would clearly be happy with a smaller house, as long as she could keep the man she married.

This has been a remarkable series of Inside No 9, and this episode is no exception. It’s the least showy so far: not a great deal in the way of bells and whistles, but underpinned with an aching sadness, the weight of responsibility, and the bruises of additional horrors that may only occur to you long after watching. Quietly brutal.