Last night's viewing - The Mystery of Edwin Drood, BBC2; Arena: Dickens on Film BBC4

According to Arena: Dickens on Film, one source of the author's appeal to film-makers was his "constellation of unforgettable grotesques". They are, the narrator continued, "characters every actor wants to play, characters impossible to overact". To which one might reply that while the first clause might be true, the second certainly isn't, and that grotesquery can be one of Dickens' besetting problems on screen. Adaptations of his work often run into trouble with the Dickensian, that caricature view of the writing that you can see in the original illustrations (which, like film or television, necessarily favour the concrete facts of the prose over its flavour). The Mystery of Edwin Drood has one big advantage in this respect, which is that it isn't terribly well known. When he plays John Jasper, Matthew Rhys isn't taking on a distinguished line of predecessors (as anybody playing Micawber would be) and very few of us at home will be waiting to see whether a beloved scene is correctly done.

The result, in Gwyneth Hughes's version, is a Dickens adaptation that feels unusually light and limber. It's less a matter of going through the canonical motions than of simply telling an intriguing story. And the performances too seem liberated by a degree of anonymity. It has its Dickensian elements, of course – in grotesques like Durdles the gravedigger – but it also has room for a kind of briskness and understatement that (pace Arena) is all too often lacking in television versions. Playing the Reverend Crisparkle and his mother, Rory Kinnear and Julia McKenzie make you feel that you're looking at real individuals, not the kind of Franklin Mint collectables that occasionally parade by in a Copperfield or a Christmas Carol.

There have been previous adaptations. Arena showed a brief clip of one in its programme, highlighting how its opening scene – an opium nightmare – is virtually written as a special-effects storyboard. Like the transmuting door-knocker in A Christmas Carol (something of a cinematic greatest hit for Dickens), it draws on one of the main currents of Dickens' imagination – the fluid boundary between the animate and the inanimate – and while last night's version was perhaps a bit rock-video gothic in style, it still captured the audacious oddity of the novel's opening, with the reader temporarily clueless as to what they've been dropped into.

Drood also contains one of Dickens' more interesting heroines, Rosa Bud, outwardly one of his doll-women but independent enough to call off a marriage that has been destined for years (and that has the excitable approval of all her peers). In a fine scene, Diarmuid Lawrence had Jasper fixing obsessively on a bead of sweat running down her neck as she sings in the parlour, indisputably a woman, not a fantasy. Gwyneth Hughes's other advantage, of course, is that there is no ending to be faithful to. She closed last night with Edwin's death at the hands of his uncle, Jasper, who wants Rosa for himself, which may have struck you as a premature revelation of whodunit, until you remembered that first scene, and its reminder that we can't always believe what we see.

Arena: Dickens on Film was a curious affair, beginning promisingly with an extended homage to David Lean's Great Expectations: "I find dialogue a bore," he said in an archive clip, implicitly making the point that Dickens was a pioneer of silent cinema in prose. In keeping with that dictum, it was nearly quarter of an hour before the programme said anything on its own behalf, offering instead a montage of clips and title cards. But then both producers took it in turns to narrate and Angus Wilson was enlisted as well, with clips from a television lecture about Dickens. It also seemed a little odd that the core of the film – the explicit debt owed by Eisenstein and Griffiths to Dickens' "cinematic" style of narrative – came so late. It's not how Dickens would have told the story.