The Weekend's TV: Being Human, Sun, BBC3<br/>Nurse Jackie, Sat, BBC2<br/>The Killing, Sat, BBC4

They've still got plenty of bite

It's that time of year when the series start returning, like migrating birds coming back from their wintering grounds.

Saturday saw the beginning of series four of The Tudors and series two of Nurse Jackie, while last night featured the return of Being Human, now in its third series and mature enough to be sporting extra plumage in the shape of celebrity guest stars – the kind of display feathers that are a reliable marker of cult success. Robson Green took a role as a melancholy and heavily scarred werewolf, kidnapped by Paul Kaye to compete in an underground cage-fighting bout, a brilliantly sleazy conceit that allowed both actors to really sink their teeth into their cameos. And then EastEnders' Lacey Turner turned up as Lia, a menacingly flirtatious spirit who guided Mitchell, the self-hating vampire, on his search through the underworld for Annie the ghost, who was dispatched to purgatory by fundamentalist Christians at the end of the last series and had been making increasingly desperate appeals for rescue.

If you're impatient with this kind of parapsychic bric-à-brac, then Being Human will probably not be for you. But there are things about the series that should hold impatience at bay, even for the most tetchily rational of viewers. One thing is its rather winning combination of dowdiness and the otherworldly, nicely exemplified here by the opening scene, in which a bored Welsh estate agent showed our heroes round the heavily foxed Barry Island bed and breakfast they were thinking of renting as their new home. Since two of them are werewolves and need a secure and sound-proofed changing room they were particularly interested in the cellar gym. "Could we have a look?" asked Nina. "It depends on how good you are at coping with disappointment," replied their jaded guide.

The other thing is the humour. Mitchell delivered the existential angst in this episode, taken on a tour of his past crimes by the victim of his latest, a bloody massacre of an entire railway carriage full of people. But George, meanwhile, was providing the light relief, having stumbled on to a group of local dogging enthusiasts while preparing for a nocturnal transformation. When he arrived in the car park with an uncooked chicken on a piece of string (a werewolf-transformation accessory), a friendly regular told him: "We don't do funny stuff here... you have to go to Swansea for that." Even if you haven't been bitten by the vampire craze, there's a lot to enjoy here.

Personally, though, I prefer the earthbound frets of Nurse Jackie, who was left at the end of the last series with her complicated life teetering on the brink of collapse. Her pharmacist lover, Eddie, had discovered that she was married and wasn't taking it very well. Even worse, Eddie has been replaced with an automated drug-dispenser, a machine that isn't going to slip Jackie a couple of packs of Vicodin on the side, in return for a regular lunchtime bunk-up. And Coop, the obnoxious houseman, is still convinced that he and Jackie have a thing going, though he's been confused by her recent behaviour. Wounded by an unequivocal knockback, Coop went off to whine to the splendid hospital administrator Mrs Akalitus (very nearly a match for Glee's Sue Sylvester in the muzzle velocity of her insults). It seems unlikely that Mrs Akalitus is going to take his complaint much further. Although she was seen to be taking notes conscientiously while Coop outlined his complaints, the reverse shot showed you what she'd written on her pad – the phrase "World's biggest asshole", repeated over and over.

The episode ended with the crash team being assembled to resuscitate an attempted suicide, routine procedure but for the fact that the victim was the lovelorn Eddie, who appeared to have concluded that this was the only way he was going to get Jackie to answer his calls. "Hey... look who's talking to me," he said weakly, when he came round to find her at his bedside. We can do this kind of dark hospital comedy pretty well too, as Getting On has recently been demonstrating. But with that series currently off air, this is the perfect replacement prescription.

The weekend also offered a new arrival, aimed squarely at those who like their police procedurals to come with subtitles. The Killing, a Danish thriller began with cliché nested inside cliché. First you got the sobbing young girl running through the forest at night. Then you got the jump-cut to the detective starting upright in bed, which makes you think (wrongly as it turns out) that the cliché was only clichéd because it was a dream. And then we discover that it's our heroine's last day on the job, before leaving for a quieter life in Sweden with her adoring boyfriend. Police detectives should always skip their last official day at work, because it invariably seems to deliver some career-threatening horror of a case, which entangles their emotions and wrecks their hopes of a quiet life.

Anyway – clichés aside – The Killing is seductively good, each episode devoted to just one day in the evolving murder investigation of a young girl, which appears to have some connection with a leading candidate in an upcoming election. Anyone with a shred of sensitivity should feel some discomfort at watching – for fun – what the parents of Jo Yeates are currently having to endure for real. But then one of the strengths of The Killing, this far in at least, is that it takes the grief as seriously as the chase.