From the moment he swashbuckled into the reimagined "Doctor Who" universe in 2005, Capt. Jack Harkness has been an immensely appealing character.

Part of that appeal stems from the retro good looks of Harkness, a mysterious space adventurer clad in the sweeping greatcoat of a World War II hero. This is just my two cents, but the blue-eyed, square-jawed, energetic Capt. Jack makes Tom Cruise look like a tired old hag.

Harkness, who’s played by John Barrowman, now has his own show, “Torchwood” (8 p.m. Saturday, BBC America), and you don’t need to know a thing about “Doctor Who” to enjoy this cheeky, sexy sci-fi romp. If you like brisk, escapist alien adventures mixed with a bit of wisecracking and some surprising forays into emotionally charged terrain, this is the show for you.

The winning yet enigmatic Harkness leads a team of young, flirty operatives who investigate alien incursions on Earth (many of these incursions just happen to take place in or near Cardiff, Wales, where the show is set). And he’s played with verve and humor by Barrowman, who hails from the Chicago area — sort of.

Barrowman's family moved from Scotland to the Joliet area when he was 8, and when he wasn’t watching “Doctor Who” on WTTW-Ch. 11 on Sunday nights, he attended Joliet West High School. It was there that Barrowman, who speaks with an American accent, fell in love with performing.

Barrowman was the well-known star of many musicals in London’s West End before he was tapped to play Harkness on “Doctor Who” two years ago. The wisecracking adventurer was an instant hit with fans, and Russell T. Davies, the creator of the reimagined “Doctor Who” series, soon spun off Capt. Jack for “Torchwood,” which has a more adult tone than the kid-friendly “Doctor Who.”

The new show was a hit in Britain, and one newspaper declared Barrowman “a national treasure.”

“I was gobsmacked by that,” Barrowman said in a July interview (to read the whole interview, go here). “I can’t believe it, but I love it. I’m totally enjoying it. Because I’m a fan, a sci-fi fan, they have made a young boy’s dreams come true.”

Stopping alien threats and “Doctor Who” foes such as the Cybermen is the usual fare on “Torchwood,” which depicts a young Welsh police officer (played by Eve Myles) who quits the force to help Capt. Jack and his crew. What doesn’t get much attention in the first season — but is treated with matter-of-fact acceptance — is his bisexuality (well, his omnisexuality, considering that he’s sometimes attracted to hot aliens). One future story line for the second season, Barrowman said, has Capt. Jack in a sexy scene with a character played by “Buffy’s” James Marsters.

“I think Jack has come across so well with the [British] public is because he doesn’t judge on that,” Barrowman said. “And he doesn’t let people judge him on that. Because he is a hero, a sexy hero with an ambition and a mission. The sexuality is completely secondary.”

Also secondary, in Barrowman’s view, is the fact the actor himself is gay. But “Torchwood” may represent a first on American television screens, according to Michael Jensen, the editor of AfterElton.com, a Web site that examines the treatment of gay and bisexual men in the media.

“The out Barrowman being cast as the bisexual Capt. Jack is a huge leap forward,” Jensen said. “To have an actor who happens to be gay playing a bisexual action hero and romantic lead on television finally gets us past those tired stereotypes of gay men as catty office assistants, hairstylists and confidants of female heroines. It’s about time.”

For Barrowman himself, being an out actor isn’t that big a deal.

“Everybody in the industry knew I was gay, but when I was asked about it because it was going to make a difference to other kids and young people who were struggling, that’s when I thought, I have to talk about it,” he said. “And I’m not making the issue of it. The [British] papers tried to make this huge, big issue about it. I talked [being gay] to a gay magazine about it, very off the cuff. Two weeks later, some newspaper called and they were like, ‘Oh my God!’ I was like, ‘Guys, it’s two weeks late, it’s old news. But it’s not really news, because I’ve always been out.’”

For those with HDnet: Kansas City Star critic Aaron Barnhart notes in his review of the show that on Sept. 17, "Torchwood" will begin airing on HDNet, which will show the program without the running-time trims that BBC America will make.

News emerged a few weeks ago that James Marsters, best known as Spike on "Buffy the Vampire Slayer," would be a guest star during the second season of "Torchwood," the "Doctor Who" spinoff starring John Barrowman as Captain Jack Harkness.

I wrote then that my fangirl brain might just explode. The guy who played Spike from "Buffy" and one of my favorite new sci-fi characters -- a swashbuckling, time-traveling, bisexual space hero -- in the same episode? It sounded too good to be true.

But wait, there's more. On Friday, I interviewed Barrowman, who grew up in Aurora and Joliet, about "Torchwood," the first season of which debuts on BBC America Sept. 8.

Here’s what he had to say about Marsters’ second-season guest spot: “There’s a scene between he and Jack when they first meet, all I’ll say is, this scene is so hot, so horny, so violent, that all the fans who watch it are going to [er, appreciate it greatly].”

I can’t put on this site what Barrowman actually said, but trust me, it made the scene sound intensely steamy.

I can’t afford for my head to explode, since there are another 12 days to the TCA press tour here in L.A., and the use of my head would be handy. But still, yowza! All I can say is, the second season of “Torchwood” can’t arrive on BBC America fast enough.

As it stands, I’ve seen the first few episodes of Season 1 of “Torchwood,” and I think sci-fi fans will find a lot to like about them. The show, which follows a team investigating alien incursions and other strange stuff happening on Earth, is a more adult, more edgy sci-fi romp than “Doctor Who.” It's cheeky yet dark and suspenseful, Barrowman is a galvanizing  presence and the entire ensemble crackles with energy.

Chicago-area sci-fi fans may be interested to know that Barrowman, who was born in Scotland but spent much of his childhood in Joliet, spent the Sunday nights of his wonder years watching WTTW-Ch. 11’s Sunday night block of “Doctor Who” episodes. So for him, it’s a dream come true to play Harkness, who stole the show when he appeared in the first season of the re-imagined “Doctor Who” franchise, which was masterminded by “Queer as Folk” creator Russell T. Davies.

In England, where Barrowman had been a fixture on the West End in stage musicals, Captain Jack Harkness and “Torchwood" are hugely popular and have “propelled Barrowman to instantaneous National Treasure status,” according to a recent piece in The Times of London.

“I was gobsmacked by that,” Barrowman said while eating French fries at the Beverly Hilton’s Trader Vic restaurant. “I was absolutely gobsmacked. All these things that are happening I just sit back and [Barrowman grins]. I can’t believe it but I love it. I’m totally enjoying it. Because I’m a fan, a sci-fi fan, they have made a young boy’s dreams come true.”

Barrowman didn't want to give away too much about what will happen to his character, but he had this to say about the season of “Doctor Who” that is currently airing on Sci Fi.

“You have to watch the third season of 'Doctor Who' [the one that is airing now on Sci Fi]. There’s things revealed about Jack in the third season which will make your pants fall off,” Barrowman said. “What happens at the end of that season of 'Doctor Who' is one of the most spectacular and biggest finales that you’ll ever come across. And it’s commenting on our society.”

One more Barrowman tidbit? He and Andy Dick were “best friends” at Joliet West High School. The mind reels.

And now here’s an edited transcript of my Friday talk with Barrowman.