The scientifically minded federal agent - sound familiar?

Jacqueline McKenzie from the show The 4400.

Even before shooting her first scene in alien-abduction drama The 4400, Jacqueline McKenzie found herself facing the legacy of The X-Files and its Dana Scully.

The Australian actress who dons an American accent as Diana Skouris — a federal agent with a medical background just like Gillian Anderson's Scully in that groundbreaking 90s show — was having problems with a vital part of her law-enforcement wardrobe.

"I'm not short but I'm petite and the gun holster they gave me looked ridiculous. It looked like I had another arm coming out of my hip," laughs the actor from her hometown Sydney.

The props department said it was time to bring out "the holster".

Turned out it was made for Scully herself.

"I was like 'ohmigod'."

McKenzie laughs at the notion of being tempted to put the prop on eBay.

When the initial six-part series, which is executive produced by Francis Ford Coppola, screened in the United States last year it was the highest-rated debut for a cable — pay television — show, drawing 7.4 million viewers.

The story follows what is presumed to be an alien spacecraft landing in the wilderness of the Pacific North-West. It returns 4400 abductees, all missing for various lengths of time and left apparently unharmed and no older since their disappearance. Imagine if there was a sequel to Close Encounters of the Third Kind and the Richard Dreyfuss character came back.

The show follows Homeland Security agents Skouris and partner Tom Baldwin (Joel Gretsch) as they trace the movements of the returnees. Some of them are having difficulty picking up the pieces of their broken lives or adjusting to life in the early 21st century. Also, some seem to have acquired special powers.

Despite the constant reminder under her arm of The 4400's chief television precedent, McKenzie says the saga is an original and more than just a sci-fi series — though X-Files fans should enjoy it.

"It's about life interrupted. We get to explore how these people get back to the life they had before. Of course they can't. I think there is so much room for it to be character-driven than a sci-fi piece. It crosses a lot of different genres and I think that's fantastic.

"It also has a good little soap element. Sure it's going to be fantastic for The X-Files audience ... because there is no more X-Files ... it's a real bummer and so it's wonderful that we can offer them something that is certainly not The X-Files but something they can really get into and enjoy.

"The impact that The X-Files had on television and on our lives when it was on — it was huge. But I believe this is as wonderful and has all the possibilities of being as big in their lives as The X-Files."

There is something post-September 11 about the show's themes — the returnees are put in quarantine with its shades of Guantanamo Bay. Once they are released, the Homeland Security agency has to monitor these civilians who may or may not be a threat to US national security.

The 4400's creator Scott Peters told the New York Times that "the heart of the piece is loosely inspired by events from 9/11. How do you deal with something like that? The scope is enormous. It touches everyone. Something that has such a large global impact, it changes us, challenges us and, like 9/11, it ultimately defines who we are by how we react to it."

McKenzie, a veteran of the Australian stage, made her movie debut opposite Russell Crowe in the infamous Romper Stomper in 1992.

But playing the smart, seemingly unflappable Kouris provided its own challenges.

"I have done a lot of roles of people on the edge of society or marginalised characters trying to fit in and recover some emotional damage. To play a role of someone who is at the centre of their world and has a very confident voice, it is actually quite a challenge for me."

McKenzie got the part after her agent sent her up for the pilot, one of the many made every year. But The 4400 got picked up, became a breakthrough hit and the biggest production McKenzie has worked on. Earlier roles included one in the BBC mini-series Stark by Ben Elton, and being an entree in Hollywood shark movie Deep Blue Sea.

McKenzie returns to Vancouver next month to shoot 13 more episodes, which she says will explore more of Skouris' character. And undoubtedly there will be more mileage to get out of the odd-couple relationship with her troubled partner Agent Baldwin.

McKenzie laughs at the possibility there could be an episode following what happened to all 4400, all over the world.

"Maybe if it's really good they can franchise it and do the New Zealand returnees."