This sitcom, with Dawn French and Hollywood's Alfred Molina playing a likeably slothful middle-aged couple, stretches The Royle Family's concept of "comedy of the mundane" to the point where it becomes almost excruciating to watch. French and Molina are brilliant and the script is believable - this week they spend several minutes discussing whether to eat a scotch pancake - but that's the problem. Nothing funny or even slightly remarkable happens. It makes Waiting for Godot look like Bad Boys II.

This week's chore occupying our heroes involves re-hanging the dining-room curtains. That leads into meditations on the place of curtains in human evolution, whether the light makes Roger look Norwegian, and the possibility that a bag of curtain hooks could be mistaken for a bag of noodles. It's tenuous, micro-observed drama but, as played to perfection by Dawn French and Alfred Molina, it's sweet, funny and at times oddly moving. There's a never-mentioned sadness in the couple's shared past and the fact that Roger's father is dying ("He won't see his tomatoes, Val") is stirring it up. But mostly, we observe the playful, trivial exchanges of a comfortably married couple.

Roger and Val Have Just Got In is set in real time, covering the half hour after a comfortably off, middle aged couple have returned home from work. Which has to be the least enticing sitcom premise ever, so maximum respect to whoever pitched that at the BBC Comedy Department.

But dismiss the show at your peril, as it stars Alfred Molina and Dawn French in the title roles, performing exquisitely observed and intricately constructed scripts by Emma and Beth Kilcoyne.

Fish fingers in the wrong fridge, a lost receipt for a vacuum cleaner and badly hanging curtains have so far provided Roger and Val with cause for conflict, reconciliation and yet more conflict.

It's engaging, rather than enthralling, provoking smiles of recognition rather than howls of amusement.

"Why are we standing here, two grown people, having a row about fish fingers?" Alfred Molina and Dawn French continue to carry this downbeat comedy with admirable restraint, tonight having an argument over Roger's bonsai seeds being in the same fridge that Val has put the tea in. It's stagey, due to its minimal set and cast, but there's a warm familiarity to its homely setting that somehow makes it work.

Pedantic botanist Roger (Alfred Molina) returns home from work to find his wife Val (Dawn French) has put his fish finger supper in the fridge strictly reserved for his seedlings. The ensuing row encompasses warring water voles, the colour of the living room sofa, and cheese and onion crisps. With just two characters and one set, this comedy series verges on the stagey. The performances, however, are finely nuanced, and the script expertly highlights the intimacies shared by long-standing couples. "You look great in a cagoule," Roger tells Val tenderly.

Tonight Roger and Val have a row. But being the characters they are, it's a slightly hopeless and unimpressive row about fish fingers, and it leaves them wishing they had more glamorous rows, as they imagine their friends do. It's hard to think of another sitcom covering this kind of territory (the episode is subtitled 'The Unglamorous Row'). In its muted character comedy Roger and Val recalls other works from Hugo Blick (the executive producer here) such as Sensitive Skin (with Joanna Lumley) and Marion and Geoff (with Rob Brydon). The laughs come from minutiae, in this case the trivial details of the way two long-married, idiosyncratic characters interact, biting off the ends of their own sentences when they're cross, stirring a teaspoon with aggressive intent or lying about something minor just to score a point. As slightly pompous, easily riled Roger, Alfred Molina is wonderful, his every mannerism believable. If he doesn't remind you of someone you know, count yourself lucky. And if, gentlemen of a certain age, he reminds you of yourself at all, you're probably not alone.

Roger and Val Have Just Got In review

Roger and Val Have Just Got In isn't the sitcom it's described as but instead a nicely pitched drama of the mundane existence of married life.

Being a TV previewer is a bit like being a royal food-taster. It's our job to sample what's on offer so you don't have to. So it's only fair we give Dawn French's new vehicle a second crack of the whip.

The bad news is it's a comedy in the same way some Shakespeare plays are comedies - that is, in the Not Even Slightly Funny way. But if you're single and miserable, you should be hugely cheered by seeing that being married can be way more tedious than living on your own.

Tonight Roger (Alfred Molina) is in a huff with Val because she's put some fish fingers and frozen peas in the special fridge he uses for his bonsai seeds. And we also learn that Val is a cookery and home-making teacher. In which case, doesn't she know that frozen food goes in the freezer - not the fridge? And what's she doing serving fish fingers for tea in the first place?

If that sounds like I'm being overly pernickety, then half an hour in the company of these two world-class hair-splitters will do that to a person.

Roger and Val have just been broadcast

Exactly as I predicted, the day your show goes out for the first time feels like both a wedding and a court appearance.

Interview: Alfred Molina, actor

Alfred Molina, or Fred to his pals, is not your typical Hollywood actor.