I wonder what it’s like to be the go-to actor whenever anyone needs a morally questionable, sappy-looking, fundamentally weak character to play the whipped dog to someone else’s headline character? You’ll always have work but … you’d have to be pretty secure in yourself, no?

But all actors are, of course, so it’s probably OK to be Matthew Macfadyen, who started his career in a 1998 TV film adaptation of Wuthering Heights as Hareton Earnshaw – Heathcliff’s whipped dog – and has been giving us brilliant incarnations of beta cucks ever since. Even when he made it to Mr Darcy (opposite Keira Knightley’s Elizabeth Bennet) it was unfortunately 10 years after Colin Firth (opposite Jennifer Ehle and coming out of a lake) had rendered all future versions redundant milksops. Most recently, of course, he gave us the greatest – oh GOD, there is no single word for Tom Wambsgans unless it is in fact “Wambsgans”, so let’s go with that – Wambsgans there will ever be, courtesy of Jesse Armstrong’s masterpiece Succession. Jeremy Strong’s intensity drew the headlines, but Macfadyen’s performance, like a worm twisting round an oiled tightrope, was endlessly clever, subtle and just as astonishing.

Anything after that is going to be, y’know, lesser, so possibly we should all calibrate our expectations accordingly for The Miniature Wife, in which Macfadyen stars as genius scientist Les Littlejohn who accidentally shrinks his wife Lindy (Elizabeth Banks) down to 6in tall. This is before he has invented the technology for restoring things to their original size. So the stage is set for shenanigans and hi (in a way) jinks.

You might also expect, given the status and capabilities of the two stars involved, that there would also be something in the way of satirical or social commentary. Lindy – a Pulitzer prize-winning novelist whom Les has forced to move from New York to St Louis in pursuit of his Nobel dreams (and ending world hunger by miniaturising crops then restoring them at point-of-sale-and-eating) – is soon confined to a dollhouse replica of their McMansion. He finds it easier to lock her in for her own safety as she screams futilely at him through a loudhailer. A dark comedy about power relations in a marriage and in a patriarchy and suppressed urges therein surely beckons.

But – nah. It’s as if showrunners Jennifer Ames and Steve Turner almost forget about this fertile conceit as soon as possible, and the possibilities it offers for oblique comic commentary on modern misogyny (sooo surprisingly different from the old kind) and give prominence instead to an increasingly screwball vibe. Which is, if anything, even harder to pull off. There is lots of stuff thrown at the wall, but little of it really sticks. There is a B-plot that doesn’t really tie in with the main, about a New Yorker short story accidentally published under Lindy’s name instead of her student’s. Just as the central conceit is wasted, this too feels like a gesture towards bigger themes – authorship, authority, truth in a digital age, age-rather-than-sex-based power relations – without developing any of them properly.

There is a carefully assembled array of Characters-with-a-Capital-C, such as the steely overseer (Zoe Lister-Jones) installed at Les’s lab to make sure investor money is not being wasted, who melts in the presence of the cat he has shrunk as a test case. There is Ritchie (O-T Fagbenle) as the incurably romantic colleague with whom Lindy has been having an emotional affair (but who is a love object for another colleague), a truculent daughter (with a secret that again merely gestures at the bigger theme of motherhood and its fraught relationship with ambition and fulfilment), and a wasted Sian Clifford as Lindy’s hardnut agent. All dutifully orbit and intersect with each other, but nothing about them or their storylines ever achieves escape velocity. And only late on in the series is Banks given anything other to do than talk to the astronaut figure in the doll house between swigs of wine from the miniaturised fridge or scream in frustration next time Les’s enormous face appears at her window.

There are a lot of set pieces – especially involving Lindy’s escapes from various vertiginous locations and vegetables exploding in Les’s lab as he attempts to find the successful restoration formula, which is always fun. But long before the end of its nearly 10-hour run you begin to feel the limitations. Ames and Turner adapted The Miniature Wife from a short story of the same name by Manuel Gonzales, but they needed to bring a lot more to the table to justify this kind of run time. Lindy might not agree, but quite often shorter is better.