How would you like your "Torchwood" -- regular or unfiltered?

The two best serial dramas to arrive on American television in 2007 so far have been cable shows: “Damages,” a thriller on FX starring Glenn Close, and “Mad Men,” a period piece set in 1960 Manhattan on AMC. That number just grew to three with “Torchwood,” a “Doctor Who” spinoff arriving 8 p.m. Saturday on BBC America.  And if you can wait another nine days,on Sept. 17 HDNet begins running “Torchwood” as well -- crystal clear and uncut.

Russell T. Davies, who created the new “Who,” has taken a shopworn premise -- a shadowy organization defends humanity from the aliens that lurk among us -- and injected two things usually missing from shows of this kind: a solid sense of fallibility and wonder and a vital dose of estrogen to go with above-average special effects and adrenaline moments. Airing on cable, “Torchwood” is the best TV show debuting here in September -- the month the networks used to own.

Gwen Cooper (Eve Myles) is a policewoman serving Cardiff, Wales, diligently if not spectacularly. One night she arrives at a murder scene only to be informed she can't go near the corpse. “Torchwood,” a cop says cryptically. (I don't think it would've helped Gwen to know that “Torchwood” is an anagram for “Doctor Who.”) Moments later, four people storm the scene, looking like they've just left a nightclub. They're carrying what appear to be a couple of toolboxes, and one of them produces a medieval knight's glove. Gwen runs to higher ground to have a look, and to her horror, the moment the glove touches the cadaver, it comes to life and the terrified victim begins blabbering.

The dead man doesn't know it, but he's only been given two minutes of life, and once those expire, so does he, again. And when that happens, the quartet vanishes, seemingly right in front of Gwen's eyes. But soon she and this mysterious group will have another run-in, and if you're a fan of the “Doctor Who” genre, you know the plucky human isn't giving up so easily.

   Soon Gwen gets a meeting with Jack Harkness (John Barrowman), the impossibly young, handsome and technologically advanced leader of the group, known as Torchwood Three, a typically shadowy and extra-governmental agency charged with defending Earth from alien invaders and tinkering with the stuff they leave behind.

  Jack shares the Doctor's disarming knack for seeming to be in control even when he's not. After Gwen manages to insinuate herself into Torchwood's bat-cave, well below downtown Cardiff, Jack blithely agrees to take her out for drinks. They take an elevator that hoists them to street level … where passersby seem not to notice them. As Jack explains, there is a “perception filter” blocking outsiders' view of the lift.

  “How does that work?” asks Gwen.

  “No idea,” Jack says with a shrug.

  Gwen is also shocked to see how blasé the Torchwooders are toward the resurrected murder victim. Jack explains that they have no interest in solving the crime, that they just wanted to try out the glove, which they found and are still figuring out. Gwen is outraged. She doesn't have the academic brainpower of Jack and his team, but she's the one with a beating heart and a moral compass, and it soon becomes clear that they need her groundedness as much as she needs the adventure of Torchwood. Also, Gwen seems to be the only one with the emotional intelligence to decode Jack, a shadowy soul with an American accent who seems to have transported here from a different time.

  “Torchwood” reminds me a bit of “Special Unit 2,” that short-lived UPN series from 2001 about a super-secret agency that fought paranormal baddies under the streets of Chicago. As for the momentary raisings of the dead, they might remind you of the promos ABC is running for its new show, “Pushing Daisies.” But we might as well be comparing my car to Clint Bowyer's. “Torchwood” is so much more tricked-out with talent and visual wizardry, and moves at such breakneck speed, and makes such demands on its viewers that it leaves most American TV shows in its dust.

  And if you're lucky enough to have HDTV and access to high-definition cable, the un-Americanized version of "Torchwood" (Sept. 17 on HDNet) should make an eye-popping difference in more ways than one. I'm thinking of the second episode, in which an alien travels to Earth for the express purpose of having as many orgasms as possible. The producers of “Torchwood” have tried to shoot the racy scenes as discreetly as possible, but you have to think there will be some serious edits done for basic cable (I've only seen the unedited version) that viewers of HDNet won't be bothered with.