Keira Knightley: Ruff and ready

The Hollywood star's new film cost just £15,000 and was filmed in one day by her co-star, the painter Stuart Pearson Wright. The actress tells Charlotte Cripps why she did it for free

Keira Knightley has made a surprising departure from Hollywood movies to star in a short film directed by the English painter Stuart Pearson Wright. The 10-minute film sees Knightley, wearing a wig similar to the one she wore in The Duchess and Elizabethan costume, battle her way through a maze, trying to find her lover, who is played by the artist.

Maze, which was made for £15,000 and filmed at Longleat Safari Park last year, will premiere next month, not at a glitzy red-carpet event but at London's Riflemaker gallery, in a show of the artist's cowboy paintings. The actress is not doing any interviews for the film – apart from this one.

"I loved the idea of doing something that was purely creative, weird and wonderful and not a commercial venture," says Knightley. "Ideas were emailed and then developed at Stuart's studio over cupcakes and tea and under the skeleton of his dog and a film piece was decided on: a collision of our worlds."

Pearson Wright and Knightley play Elizabethan courtiers, Edmund and Constance, whose frustrating inability to find each other in a maze is presented as a metaphor for a relationship breaking down. The playful opening sequences would fit a demure and elegant period drama, but the mood shifts to something far more gritty. Separated by tall hedges, the pair cannot reach each other, despite Knightley's longing cries of "Come hither, Edmund!" and wild chases along thin pathways.

"Stuart referenced various films for the mood, film by Werner Herzog as well as Possession with Isabelle Adjani – particularly a scene in which she miscarries the devil's child in a subway station," says Knightley. "My direction on the day often consisted of 'a little more Adjani' and although we never quite went as far as the abortion of green goo, there's always the sequel."

At one point, a forlorn Knightley becomes wedged between two narrow hedges and her hair is caught in another. She tries to bore her way through the shrubbery, almost comically, to get to her lover on the other side. He fails dismally to jump over it. Finally, he gives up, unable to rescue her. She walks away alone in a final scene that references The Incredible Hulk.

Knightley, who recently made her West End debut in The Misanthrope, filmed Maze in a day, having waived her usual fee. Her dressing room was a bedroom in a local B&B and she ate, while wearing full Elizabethan costume, with the 16-strong film crew in the Safari Park's canteen.

It was an incredible leap of faith for a Hollywood star to put her trust in a first-time director. Pearson Wright won the BP Portrait Award in 2001, when he was just 26. His fans include Charles Saumarez Smith, the secretary and chief executive of the Royal Academy, who was once in charge of the National Gallery. Saumarez Smith called Pearson Wright "an exceptionally talented figurative artist, working in a way which is highly meticulous, but also with a strange visual imagination".

Many actors and stars have sat for Pearson Wright, including John Hurt and JK Rowling, whose portraits hang in the National Portrait Gallery. But until Maze, he had never directed a film.

"Part of the reason for me wanting to use an actress like Keira is her association with period dramas," he says. "Those associations are important, to lull the audience into a false sense of the familiar. The juxtaposition of a Hollywood actress in period costume with a very contemporary shooting style, being jostled about by a jumpy camera, is an incongruous and uncomfortable one."

The pair met in the dressing room of a mutual friend, Rosamund Pike, when she starred in Gaslight at the Old Vic in 2007. Knightley says: "Stuart was wearing plus-fours and I thought it an extraordinary thing that someone had the balls..."

Nevertheless, they went out for a meal, along with Knightley's partner, Rupert Friend, and Pike. Knightley found herself sitting next to Pearson Wright, whose work she admired. "I first came across Stuart's work in French's [theatre] bookshop, where I picked up a copy of his drawings of actors, which I loved," she says.

Soon afterwards they met again, at a party hosted by their friend Joe Wright, the director of Atonement, "at which we formed a band with kids' instruments; I the kazoo, he the plastic trombone" says Knightley. They discussed potential projects.

Pearson Wright was blown away when Knightley agreed to star in his film. She and Friend visited his east London studio. To give her some idea of what he had in mind, Pearson Wright showed her Knight's Tale, which was filmed on video by his ex-girlfriend and which features him dressed as a knight in clanking armour, lost in a forest.

"I was impressed Keira agreed to do the film straight away," says Pearson Wright. "She had the humility to take direction from somebody who lacked experience."

Maze will be exhibited in the artist's new London show, I Remember You. Knightley and Pearson Wright will appear on two very large screens at opposite ends of the room. With feature-film sound, Maze is so sophisticated that viewers will think a real bee is in the space, buzzing from from one side of the room to the other.

The film will be shown alongside Pearson Wright's cowboy paintings, starring the artist and his fiancée, Polly, and inspired by stills from films including John Ford's The Man Who Shot Liberty Valance. Pearson Wright has also recorded some county and western hits for a limited-edition LP, Lonesome Stu & The Gearshifters Sing Good 'Ol Country which he will perform at the private view and the film's premiere.

Role-playing is central to Pearson Wright's work – in his paintings, drawings and recordings he portrays archetypal heroic figures in an attempt to heal an "identity void" caused by his having been born through artificial insemination.

He says: "These feelings of insubstantiality and inauthenticity that plagued me as an adolescent have been transformed from existential fears into something to be revelled in: a great, bounding game of role playing, sometimes tongue-in-cheek, sometimes grave, but never earnest, always with a knowing sense of the absurdity and the fiction inherent in the idea of identity. I realised the importance of being able to examine one's own identity without taking oneself too seriously. It is principally the necessity to laugh at oneself: at one's vanity, follies and fears."

The artist, however, recalls being overcome by fear and panic before directing Knightley. "I hadn't directed a film before – let alone a Hollywood actress. It was one of the biggest days of my life. I was standing in my bedroom at the B&B thinking, 'How the hell did I manage to get myself into this situation?'".

Luckily, a maze advisor guided the film crew and Knightley through 1.48 acres of more than 16,000 English yews. But Knightley and Pearson Wright had to improvise Elizabethan dialogue, in some cases in only one take, and filming had to be completed in one day.

The expensive but cumbersome Elizabethan costumes were made from scratch by the costume designer Oliver Garcia, who worked on The Wolfman, starring Emily Blunt. Originally Knightley was to wear a red wig but in order to steer clear of associations with Queen Elizabeth I, a wig was made to match her natural auburn hair.

"She was as un-divalike as anybody could be, because she is so down to earth," says Pearson Wright. "She is not into playing the whole star game. She genuinely loves acting and I think she gives a great performance, in this film, in a very uncomfortable dress."

If nothing else, the experience proved to Pearson Wright that making a film is possible. He does not, however, intend to branch out into features.

"I love painting too much," he says. "But Keira is up for sitting for a painting next."

'I Remember You', Riflemaker, London W1F (020 7439 0000; Riflemaker.org) 5 May to 26 June