Last Night's TV: Silk, BBC1; Treme, Sky Atlantic; <br/> Heston&rsquo;s Mission Impossible,Channel 4

When it's worth staying on the case

Silk, Peter Moffat's enjoyable legal drama, began with its barrister heroine receiving some briefs. One set – a frilly polka-dot pair of knickers – came in a small Jiffy bag and hinted at recent sexual adventure.

The other set – about three-and-a-half feet of messy files – was thumped on to her desk by Billy, the chambers clerk, condemning her to a long night of reading before next day's court sessions. Fortunately, despite those insinuating knickers, Martha Costello didn't appear to have much of a life outside work. She returned home to an empty flat, tossed a ready-meal into the microwave, and settled down to prepare. She also drank a beer straight from the bottle, so that we would know she's a no-nonsense ballsy type who isn't going play by the conventional rules. Which would all have been a bit depressing, frankly, but for the fact that Martha is played by Maxine Peake, an argument in mitigation in itself.

Martha is an idealist. "Innocent until proven guilty. Four words to live by," she tells her new pupil. So naturally she was the barrister who ended up defending a sleazy lowlife accused of battering a pensioner round the head. He was the defendant from hell and his alleged victim was the kind of witness defence lawyers have nightmares about, a decorated Normandy veteran who delivered his testimony with calm military exactitude. Martha's day hadn't started well either, since she was stabbed in the back by a chambers colleague in the previous case. So how would she win the day? By treating a frail, bruised old man as a hostile witness and prising open a sufficient gap in his testimony to finger the police for a fit-up, as it turned out. "These two things are true," she told her uncertain pupil as the lowlife smirked at his acquittal, "Gary Rush is a horrible man and it's right that he gets off."

It seems to be more complicated than that. Martha was right that the evidence was rigged, possibly wrong about his innocence, and the "next week" spoiler suggested that Gary is going to be a continuing presence in the series, adding another narrative strand to the ongoing battle between Martha and her cynical, ex-Harrovian, coke-snorting colleague to see who can take silk first. As Billy geezerishly pointed out, Martha has a handicap in this race: "Two hundred and forty-five women silks ever," he said, "It's still 12 male QCs to every Doris... I mean, what are the odds?" Long, I suppose we're meant to conclude, but given that Martha triumphed against adversity in every encounter here – including humiliation by a lethally cocky solicitor and our assumption that she'd been too soft-hearted about a female drug mule – I have a feeling that she might take it by a neck.

I was a little wary about Treme, David Simon's much ballyhooed follow-up to The Wire. For one thing it seemed unrealistic to hope that lightening would strike twice. For another thing I wasn't sure that I could listen to quite as much jazz as this series was obviously going to require. And the opening minutes of his account of a New Orleans neighbourhood suggested there could be another problem: the sound mix of foreground music and authentically drawled Southern vernacular meant that only about one word in five actually got through. So – though the credit sequence is terrific (a strangely lovely montage of flood-damaged walls) and the setting startlingly at odds with what American television conventionally regards as sexy – I wasn't convinced it would take. Confidence took another battering with the appearance of a British reporter, who demonstrated that however good Simon's ear is for local speech patterns he's completely cloth-eared when it comes to condescending British television journalists (they exist, God knows, but they don't sound anything like this).

I'd reckoned without the quality of the thing, though, and the slow simmer of characters who don't appear heavily outlined as types (good cop, bad cop, idealistic barrister, say) but with the opacity and ragged edges of real life. Is Davis, a local DJ and music enthusiast, a self-indulgent asshole or charmingly feckless? Far too early to say, which is sufficiently intriguing to make you want to stick around for more evidence. And what are we to make of the other relationships, between Antoine the trombonist and his tough LaDonna, and Janette, a local chef, and Davis? It hasn't yet definitively proved that it's love of New Orleans doesn't buy in to the city's self-mythologising, but it has certainly established that Simon's ability to control a complicated urban narrative wasn't a one-off. I even found myself enjoying some of the music by the end, which suggests that it's biggest task, to make adoptive New Orleanians of every viewer, had been pulled off in one case at least.

The point of Heston's Mission Impossible is that Heston proves it wasn't impossible after all, though if this first episode is typical they'll fudge like crazy to make it so. His task was to improve the food in a children's hospital, in the teeth of employee defeatism and tight budgets. Naturally, the end result was presented as a vindication of his suggestions, though the fact that one of his recipes involved injecting fried meal-worms with ketchup by hand suggested that his triumph was very unlikely to be repeated daily and quite impossible to achieve on a budget of £3.34 a head per day. Its dodging of hard facts in the interest of synthetic victory left a distinctly unpleasant taste.