-Three years ago, Andy Deere got a phone call from a Whanganui school friend.
"He said, 'Are you guys doing any filming? Because I'm doing this interesting sport that would look good on film'."
Deere had no idea what his old mate was talking about. "I never even knew this existed," he says. "I don't think a lot of people would."
But his interest was piqued when Deere's friend explained his love of medieval combat, a sport that involves opponents strapping up to 40kg of armour to their chests, stepping into a ring and belting each other with metal weapons.
Deere hadn't heard of the sport and he didn't know his friend was involved.
But it was a phone call that led him and Ryan Heron to spend the next two years filming an undiscovered Kiwi subculture.
"We sort of thought, 'Let's just do it'," says Deere. "It sounds bizarre, but that's how it happened."
The result is Bludgeon, a feature-length documentary that debuts next week as one of the most anticipated Kiwi films appearing at this year's New Zealand International Film Festival.
The film follows New Zealand's top-ranked team, Taranaki's Steel Thorns, as they pursue the goal of a world title at the world champs in Denmark.
It's told through the eyes of new recruit Nick Waiariki, who is trialling for a place in the Thorns. "They can fight," he says early in the film. "Being part of that would be a privilege ... I hope I tick all their boxes."
Deere and Heron initially agreed to film for two days, and got enough content for a three-minute short. But they always knew there was more to their story. "We just kept going," Deere says. For two years.
There are those who think it is simply cosplay, but Deere is against calling the combatants nerds. "They're geeky, they're into medieval re-enactment, they love the time period, but they're also quite physical and want to take it to the next level," he says.
His film captures the brutal fights and the aftermath, when competitors often require hospitalisation.
"For them, it's a very serious sport and you can tell just how passionate they are about it by how they switch into game mode on the day. It tends to be high impact."
So why do people do it? To answer that, Deere quotes one of the stars of his doco.
"He says, 'We have too much shit these days. Oh, my iPad's broken, oh my phone is broken'. In medieval times, you just had what you had. There's something primeval about it."
Kiwi documentary Bludgeon has it's debuts as part of the NZ International Film Festival on Tuesday at Event Cinemas on Queen St at 6.15pm.