Musician Example has said he signed up for ground-breaking "social cinema" movie Shield 5 because it is "genius".
Instagram is the only platform where the film consisting of 28 episodes each lasting 1 5 seconds is available.
A new episode of Shield 5 will be released each day this month on the social media site, accompanied by a photograph intrinsic to the story.
Talking to the Press Association about his role as Ray, Example, real name Elliot Gleave, hailed the innovation.
"I thought it was genius," he said. "Instagram tends to be celebs doing videos of themselves and selfies, so I loved the idea - it's very bold."
Shield 5 stars Christian Cooke as security driver John Swift, who ends up accused of murder.
Creator Anthony Wilcox, of Hello Carter fame, also directed the project, which was written by Adam Dewar.
Wilcox, an Instagram user, said the idea for Shield 5 was born when he took on some online projects while developing his next feature-length movie.
The fast turnaround from shooting to an audience seeing the finished product was, he told PA, "refreshing and invigorating".
"It dawned on me that no-one had utilised Instagram in the way of telling a dramatic story. There's potentially a big global audience built in and users that aren't used to seeing that type of content on the platform," he added.
"I did quite a lot of research and looked at some film trailers and advertisements that were 15 seconds long and quickly realised that, if you're clever, there's a lot of story you can squeeze into any 15-second slot."
Shield 5 star Cooke, who featured in 2013's Romeo & Juliet alongside Douglas Booth, has seen the seven-minute finished product.
"Each 15 seconds is about giving the audience another piece of the puzzle and try and entice them enough to come back and watch the next one," he told PA.
"It's very experimental," he added. "It's high concept, there's a soundtrack, special effects and the production values are incredibly good. It has all the elements of a feature film or a television show - it's just that it's made for Instagram."
Cooke said the length of the individual instalments put restrictions on the script: "There's no 15-second love scene as such, but there is a post-coital 15-second scene. That you can do."
Example, who has said he would like to make a career out of being a character actor, said: "Shield 5 is not necessarily a film where, as an actor, you get much time to shine because there's very little screenplay and dialogue so you don't get a chance to develop much sense of character."
He went on: "I thought it would be a good thing to have on my CV, great director to work with, a really impressive cast and I'm very pleased with the results. Time will tell whether it's a good idea or not."
Director Wilcox said it is hard to anticipate how Shield 5 will perform.
"People are really, really intrigued and interested, but can't quite get their heads around what we've made. However much I try and explain it, I think the proof of what we've done will only be in the viewing of the episodes themselves."
:: Shield 5 is available to watch here https://www.instagram.com/shieldfive/