Hunderby, Sky Atlantic, Monday, 10pm / Bad Sugar, Channel 4, Sunday, 10pm / Good Cop, BBC1, Thursday, 9pm

Julia Davis's dark reworking of du Maurier's 'Rebecca' is funny, clever, and absolutely filthy

Of all the mysteries in Julia Davis's latest series, Hunderby, perhaps none can trump that surrounding its revered creator.

How, interviewers have repeatedly wondered, can the reserved, self-deprecating woman in front of them be the same one responsible for some of the most disturbing TV comedy of the last decade? Chiefly Nighty Night, the sadistic sick-com which saw a deranged suburbanite breaking up marriages, poisoning priests, and inseminating herself with semen-spattered pie and mash. And then Lizzie and Sarah, a 2010 pilot about two abused wives whose wet-weekend-in-Dungeness levels of bleakness convinced the BBC to schedule it in the treasured time-slot prefacing late-night Ceefax.

Well, the plot only thickens with, Hunderby, which is less overtly shocking than those previous works but just as bizarre: a Gothic burlesque both finely mounted and fetidly imagined. Set in "the year of the Lord 1831", as the sonorous narration has it, it tells the story of a shipwrecked, amnesiac ingénue (Alexandra Roach) who washes up in an English coastal village and falls into marriage with its widowed pastor, Edmund. But her real misfortune is to have been cast into a particularly demented riff on Daphne du Maurier's Rebecca, complete with devious housekeeper Dorothy, played by Davis herself, gruesome meal options, and endless servings of verbal and physical humiliation. "I take much comfort from your simplicity ... both of looks and character," Roach's hubby-to-be tells her early on, getting things off to a deliciously inauspicious start.

The script, needless to say, is one, long zinger, parodying high-falutin' costume-drama diction with an exquisite mixture of savagery and scatology. I loved Edmund's excruciating comparison of his first and second wives' pudenda: "Arabelle was smooth as ham – nature did not busy her broken mound with such a black and forceful brush". And Dorothy's sombre update on her master's mother's medical condition: "Her bowel has still not spoken, Sir ... though I fancy I caught a whisper." I could go on – and certainly will outside this column, so watch out friends, colleagues and quote-haters! – with countless other lines, whose surreal artistry you wanted to roll over your tongue and savour. Meanwhile Nighty Night fans will know what I mean when I say that the phrase "bubbly milk" could well become the new "Hiya Kath!"

But will the series have the impact of that cult favourite? Probably not – for all its perverse imagination, the tone is more muted, the humour less obvious and the literary conceit possibly more limiting. Though what chance it has rests with Davis's fabulously callous Dorothy; with her Medusa-like stare and simmering sexual pathology, she makes Mrs Danvers look like Mrs Doubtfire.

On the other hand, not even Davis could rescue star-studded self-indulgence Bad Sugar, written by Peep Show duo Sam Bain and Jesse Armstrong and the centrepiece of Channel 4's presumptuously-titled Funny Fortnight. The problem was the premise: a spoof of the telenovella, which, for the uninitiated, is a type of high-camp, short-form Spanish-language soap opera. Which prompts at least three questions: first, who has actually seen a high-camp, short-form Spanish-language soap opera? Second, why spoof a short-form, high-camp Spanish-language soap opera with British characters in a British locale? And finally, does high-camp, short-form Spanish soap opera not fall somewhere beside Donald Trump in the beyond-parody stakes? And so it was that, without any decent material to play with, a blue-chip cast (Davis, Sharon Horgan, Olivia Colman, Reece Shearsmith) mugged away exhaustingly. The pilot began with a fake "Previously on ..." montage, although I assume the corresponding "Next time on ..." montage was for real since a full series lies ahead. Which makes you wonder if all the good comedy commissioners have scarpered to Sky Atlantic.

And finally: another week, another cop drama. BBC1's new four-parter Good Cop was trailed with the USP that it focused not on a maverick detective, but an ordinary bobby. Other than that, though, it was all entirely off-the-peg: think speeded-up traffic shots, underlit interiors, lashings of dramatically climactic rain, smirking gangsters, and impulsive but fundamentally decent heroes. When it comes to the small screen, the Emperor's New Clothes are truly the Policeman's New Uniform.