When it comes to your favourite music artists, chances are you probably know a lot about their lives.

But there is an air of mystery around one of the headline acts for next year’s Download festival.

Masked mystery.

British metal group Sleep Token will be topping the bill in Leicestershire, along with Green Day and Korn.

It is the first time any of the three headliners have been the main acts at the rock gathering.

Sleep Token – who formed in 2016 – are known for performing in masks to keep their identities hidden, and have created a buzz in particular.

A search online gives no easy answers about them, with various theories floating around some of their identities – often citing “research and analysis”.

“I think it’s a big part of the attraction because no-one knows who they are,” says fan Devon, from Plymouth.

“It gives a lot of people a chance to see them. I’ve always wanted to see them and Download’s just an amazing opportunity.”

Devon, 25, tells BBC Newsbeat “the massive bands like Iron Maiden, Metallica, and Slipknot” often take the headline slot, and the change is good.

“Don’t get me wrong, I absolutely love those bands, but it’s nice to have something new for once.”

There has been some criticism about not having some of those traditional acts, but Devon feels it’s a case of “people don’t like seeing new stuff coming out”.

Gareth, from Cardiff, has been a fan of Sleep Token for five years and is excited to see them.

He feels the group “have moments of real sombreness” mixed with the heavy metal.

“I guess when they started, they were supporting the headliners [at the time],” Gareth, 22, says.

“It’s so good to see the evolution of a band from playing in small venues to them now having millions of monthly listeners, and also to headline what is probably the biggest metal festival in the UK.”

Other acts due to perform include McFly, Bullet For My Valentine, Don Broco, Sex Pistols, Alien Ant Farm, Spiritbox, Poppy and CKY.

Alyx Holcombe, presenter of BBC Introducing Rock on Radio 1, describes the new line-up as “refreshing”.

“It feels like we are going in the right direction for rock music,” she tells Newsbeat.

“The music is like something that I don’t think anyone has really ever heard before. It’s quite a new sound.”

And she’s a fan of the “clever” mystery masks because it “creates intrigue”.

“I think it adds a layer of mystery and curiosity as to why are all these people in masks.

“I want to know who is creating this amazing music, and it creates a mass fandom,” she says.

Headlining Download brings Sleep Token into the “big leagues” of rock, Alyx says.

“I think it’s a statement that Download have put out.

“Like actually, Sleep Token are as good as all these other bands, and you should get on board with them.

“It would be a dream for anyone, and to be next to Green Day and Korn, I know they’re absolutely stoked about this,” she says.

Download festival is due to take place at Donington Park, Leicestershire, between 13 and 15 June.

Listen to Newsbeat live at 12:45 and 17:45 weekdays – or listen back here.