There is no guarantee that good original material will make for a good adaptation. Nor, more inspiringly, will a second-rate work necessarily result in something second-rate in another medium. The Da Vinci Code with Tom Hanks may not have been his finest work, but the film could not have been made worse than its source material (see also Twilight and Fifty Shades of Grey). In TV, perhaps the most consistent proof of the pudding has been in the many successful adaptations of Agatha Christie there have been – most notably and recently by Sarah Phelps, whose rich, dark versions of the murder mysteries have become a much-anticipated Christmas treat. They work, in part, so brilliantly because you can really only add to Christie. She is not Dan Brown, but as primarily a plot machine whose protagonists are ciphers in its service, she is closer to that end of things than the other.

Now Phelps has turned her hand to Dublin Murders (BBC One), an eight-part adaptation of In the Woods and The Likeness, two very good books by Tana French, an author very much at the other end of the scale. They are the first (and best) two thrillers in her Dublin Murder Squad series, and are among the most intricately plotted, beautifully written and psychologically acute examples of the genre that you will find. There is little to be added to such fine-grained work – and much to be lost. French is a delicate builder of characters’ interior worlds, a precise mapper of the endlessly fascinating convolutions of both ordinary and murderous minds. None of this translates readily to the screen. That is not a fault; it is innate to the two mediums: one primarily visual, the other not.

It is not clear yet whether she has found anything to add to French’s work, or a way to reproduce all that, in careless hands, is in danger of being lost. But if we judge the first episode, as is probably fairest, as that of a police murder-mystery series, it is a sophisticated and slickly satisfying operation.

We open with a man in a basement in the throes of a breakdown, watched by an expressionless young woman as he mutters desperately. “What if the killed are the lucky ones? The chosen … and the rest of us aren’t lucky at all?” “We won’t see each other again,” she replies, and leaves. We then rewind to four months earlier and begin the meat of the thing.

The pair are Garda detectives Rob Riley (Killian Scott) and Cassie Maddox (Sarah Greene), who find themselves in charge of a murder investigation when a 13-year-old girl, Katy Devlin, is found dead in the local woods. Everyone wonders if there is a connection to the disappearance of three children – Adam, Peter and Jamie – 20 years before, whom we see in flashback playing and becoming separated in the woods before their presumed abduction. Only Adam reappeared, covered in blood not his own and with his T-shirt deliberately slashed. The other two have not been seen since. Adam was never able to tell anyone what happened or where they might be. “Gone under the hills with the old ones,” as an old lady who knew them says, is all the explanation they have.

Questions large and small are flung into the air and expertly juggled against a well-conjured backdrop of increasing dread. Why is Cassie adamant that she and Rob cannot investigate this case past the preliminary stage? What precisely is wrong in the unsettling Devlin household? Who is the man prowling around Cassie’s flat, and what are we to make of Rob’s dreams of wolves hunting him through forests at night? Is Mr Devlin’s connection to the protesters against the coming motorway that will destroy the woods significant? And what is the link between the homeless man daubing: “He rises. He rises,” on the billboards and the businessman who threatens to have him kneecapped if he reveals any of the secrets that seem to be torturing him. And how many viewers will have guessed the twist in the final scenes before it comes?

It is a tasty slice of cut-and-come-again cake, even if the relationship between Cassie and Rob – upon which the credibility of the story turns (or will, if faithful to the books) – is not yet sufficiently close or well-drawn. But it is a fine one to curl up with and enjoy as the nights draw in. And if it stirs in you the urge to devour the French originals, too, I promise you will find something even more richly delicious there.