First came the actor, then the British director. But if you live and die for fashion, a documentary called “McQueen” could tell only one story, that of designer Alexander McQueen, whose extraordinary gifts, dark preoccupations and tragic death make for a completely engrossing, compulsively watchable film.

Even if the dramas and dictates of couturiers and catwalks mean little to you, it is hard to resist the propulsive energy that director Ian Bonhote and co-director and writer Peter Ettedgui bring to the story of a designer whose background, beliefs and gifts were not what one would expect.

Growing up in London’s nonposh East End, the youngest of six children of a cab driver, McQueen wrestled with demons from childhood. He committed suicide at age 40, a time when success was at his beck and call.

Rather than flee that darkness, McQueen used it as the essence of his creativity: “Everything I do is personal. You want to know me, just look at my work.”

His gifts were visible from early in his career. “No one discovered Alexander McQueen,” a friend says. “You don’t discover talent. Talent is there. Alexander McQueen discovered himself.”

In this, the designer and the documentary bear a resemblance to Kevin Macdonald’s “Whitney,” another illustration of the reality that great ability does not ensure happiness; both feature individuals everyone knew were in trouble but no one was finally able to help.

Indifferent to school but always drawing clothes, McQueen, whose first name was Lee, was encouraged by his mother, Joyce, to apply for an apprenticeship with the tailors of Savile Row. Not only did he get a job but he also proved to be gifted as a cutter of fabric and, though he lacked the necessary language or sufficient funds, decided Italy was the next step.

There he wangled his way into a job with top designer Romeo Gigli, who says, as does everyone who knew McQueen in those early days, “he was deeply looking to understand everything.”

Key to McQueen’s evolution was Central St. Martins art school in London, a city he knew inside out, from its gay bars to where the best buttonholes were made.

At St. Martins, McQueen did a student show, “Jack the Ripper Stalks His Victims,” that astonished with its daring and bleak worldview.

“I didn’t care what people thought of me,” the designer said later in his career. “I would go to the end of my dark side and pull these horrors out of my soul and put them on the catwalk.”

Among those seeing the show was Isabella Blow, a key player in British fashion and an early champion. “I wanted them,” she says in a later interview. “I rang up his mother and said, ‘You produced a genius.’ I called six or eight times a day; they thought I was a mad person.” She ended up buying the entire collection.

For his first professional collection, when he was 22, McQueen used unemployment benefits to buy fabric, which meant he couldn’t show his face on camera because he would be busted for working while on the dole.

Harum-scarum as these early days were, they seem to have been the happiest for McQueen, who was eager for success but did not always react well to it, especially not to the money that allowed for increased drug use.

A turning point came in 1997, when he was given the reins at Givenchy, the storied Paris design house. Among the things he did was fund his personal Alexander McQueen line, but the inevitable work pressures were not a good thing.

Sympathetic to the designer, the filmmakers persuaded many of McQueen’s friends and collaborators to talk on camera and used a propulsive Michael Nyman score to good effect.

As recounted in the film, aspects of McQueen’s life call up other associations. His love of falconry recalls Ken Loach’s “Kes,” and his suicide in 2010, a week after the death of his mother, is reminiscent of the death of pulp writer and Conan creator Robert E. Howard.

But finally, Alexander McQueen was sui generis, one of a kind, which is why more than a million people turned out in London and New York to see a posthumous exhibition of his work, and why this striking documentary is hard to get out of your mind.