It's been decades since Martin Henderson walked the halls of Shortland Street and now he's back for the show's 25th anniversary, he feels like an "alien".
Sitting down with Henderson after his first Shortland Street shoot in 22 years, he's still "reeling from the experience".
"I'm still trying to figure out how I feel about it because it is oddly familiar but also there's been so much water under the bridge, so many years. So I feel like a bit of an alien in a way, like a ghost," he says.
Henderson was part of Shortland Street right from the start in 1992.
His first day on set, he was "terrified" and feeling the pressure of starting something, he says, was "the first show of its kind in New Zealand".
When asked if he thought then that Shortland Street would last long enough to see its 25th anniversary, Henderson gives a resolute: "No."
"No, no. Not 25 years," he says, admitting that the show wasn't warmly received in its early stages.
"I was really disappointed it wasn't better received because I was really proud of it," he says.
"But then it just sort of...people started to pay attention and fall in love with the characters and it took off from there"
He credits that in a large part to producers like the late Caterina De Nave, who helped found the show.
"She was an exceptional woman and I think the show's initial success was down to her insistence that it needed to be culturally relevant. She was very concerned with the zeitgeist and she wanted to have that on screen," says Henderson.
"She wanted Kiwis to go home after work and turn on the TV and see themselves on the screen and see things being played out on Shortland Street that were happening in real life, and to be a part of that just felt like a real honour."
After his three-year stint on the show, Henderson went on to work in Australia on shows like Echo Point and Home and Away before eventually making his way to the US where he stars on hit TV series Grey's Anatomy.
But he comes home often in an effort to stay connected with friends and family, and to "pay heed" to the show which ultimately launched his career.
"If it wasn't for Shortland Street I don't think I would've had a career as an actor," he says.
"It was such an important part of my life and journey - if it wasn't for my years on Shortland Street, it wouldn't have propelled me to the next stage. There is a connective tissue between each job and each decision, whether it's literally the people you meet or the confidence you gain; it's nice to stay connected to that."
Henderson had acted before Shortland Street, but never as part of a full-time, long-term career.
He wound up on the show after finishing high school early and taking a gap year before uni. The plan was to work on Shortland Street for a year and make enough money to put himself through university where he was planning to study science and business.
But he fell in love with acting and "it just sort of became the thing", and "all of a sudden, uni became an old dream".
"Before that, it was this hobby. I'd never trained, I didn't necessarily feel that I was qualified, but by the end of it I didn't doubt whether I was an actor, my confidence had grown so much that I was more than willing to try my luck as an actor," he says.
It also set him up to deal with fame and celebrity in a way only a Kiwi show could.
"I was 17...that level of attention or celebrity was something that I don't think anyone can really prepare themselves for, especially at that age," he says.
"It was kind of a baptism of fire, being thrown into this fishbowl, because of course New Zealand is so small that there was just so much focus on us, and while it was fun and flattering initially, it very quickly became difficult to contend with. But I always maintain that it gave me quite a good taste of that side of things before I went off into the world."
And now that he's back, 22 years later, things have changed.
The location is different - the show used to film in Browns Bay and is now in West Auckland - the crew is different and so is the cast, but there are still some familiar faces and Henderson isn't the only cast member returning for tonight's anniversary special, though everyone is remaining tight-lipped on details.
All he'll reveal is: "Family matters call Stuart back to take care of one of his own", but he does hint at a "little attraction in the corridors" to "keep things spicy".
One thing's for sure, Henderson is no longer so quick to discount Shortland Street's lasting power, saying if the writers continue to keep it fresh and relevant, we could well be sitting down together again in another 25 years.
"I don't see why Shortland Street couldn't last another 25 years, it's become an institution in a way, it feels like it's here to stay."
What: Martin Henderson returns for Shortland Street's 25th anniversary special
Where: TVNZ 2
When: Tonight at 7pm.