He only seems to have spent five days on the job, but it seems like five years for actor Carlos Bernard.

Because that's what happens when you're in the cast of 24 , the real-time counter-terrorism thriller which is now in its fourth season here (8.30pm, TV3), while Bernard is already working on No 5.

Yes, he's surprised the show is still tick tick ticking along - he's also signed up for a sixth season.

"I couldn't imagine it going beyond a sixth year, then again I couldn't imagine it going beyond a first year," he laughs down the line from a Los Angeles freeway. "So what do I know?

"It's funny. We've been shooting since July and don't air in the US until January. We always get to this point in the year thinking 'This season is just going to suck' and we're so afraid of that. We are just trying harder and harder to make it better. It's always a big challenge to keep it up to snuff."

As agent Tony Almeida, Bernard is the only surviving member of the original series apart from lead Kiefer Sutherland as Jack Bauer.

Bernard's guy has been through a lot over the years - getting fired from the Los Angeles Counter Terrorism Unit (CTU), jail, divorced from fellow agent Michelle Dressler, presidential pardon, unemployment and hasty reinstatement to the job a few episodes back.

Tonight's thrilling instalment shows Almeida is very much back on the CTU career ladder.

Low-key until now, Bernard's career has revolved around 24 and its 10 months-a-series shoots for the past few years. Though sometimes the show has occasionally adapted to him - like when he once came back from a Christmas break on crutches after he badly dislocated his foot playing basketball.

"I couldn't put any weight on it so I had to be on crutches for three and a half months while it heeled. When I got back there was meant to be this knock-down drag-out fight between Jack and Tony, and Kiefer had a broken knee cap at the time.

"So it ended up being probably the lamest fight in the history of television. It was one on those things where he sneezes and I fall over and he kicks my ankle to justify my injury."

That was in the second series. Bernard thinks the current fourth one, with its story of terrorists sending United States nuclear powerplants into mass meltdown, is the best yet.

"The first season was meant to be about the assassination attempt on President Palmer - it was meant to happen in the 24th episode but it ended up happening in the seventh, and so I think that every year the writers have learned a bit more about how to plot it out.

"I think they used the best elements from the first three seasons. This year they've used the best balance of action, intrigue and character."

The fourth series also seems to have many a scene involving torture, just as the United States debates the use of "enhanced interrogation techniques" by its forces in Iraq.

"I think that definitely there's been some strange coincidences in stuff that we have shot and has later come to pass. I think it plays upon our biggest fears of terrorism really.

"But in the end it's nothing more than fantasy - a spy novel in a sense."

Does he think the show, more than just playing on it, actually contributed to the climate of fear about terrorism?

"Um. I don't think so. I don't know. I'm too close to it to be able to really say. We do stretch the envelope of believability and people realise it's just entertainment."

Still, all that secret agent paranoia has rubbed off on Bernard just a little.

"I do check people out a lot when I am getting on planes. There are certain situations where I feel a little odd, I'm definitely a little more suspicious."

By Russel Baillie