John Cameron Mitchell meets Neil Gaiman, and the collaboration results in a period coming-of-age movie with sci-fi trappings that’s less a splashy glam bomb than an irritatingly outré damp squib. “How to Talk to Girls at Parties” may join two creators with distinctive sensibilities—Mitchell was responsible for “Hedwig and the Angry Inch,” while Gaiman is something of an icon among sci-fi writers and graphic novelists. But in this form it manages only to show each at his worst.

To be fair, the fault doesn’t really lie with Gaiman. The short story that served as inspiration for the movie, which won a Hugo Award in 2007, is a hallucinatory, dreamlike piece about two fifteen-year old guys crashing a party and interacting with a chain of strangely hypnotic girls before running back home. It’s a deceptively simple, weirdly engrossing piece. In expanding it, Mitchell and his co-writer Philippa Goslett have fastened onto stray throwaway bits in it and brought them front and center, while turning its central enigma into a clumsy parable of individuality versus conformity, told with no wit and the lightness of touch one might expect from a bulldozer. It’s a movie striving to become an instant cult classic, and failing miserably.

Set in 1977, it’s about a trio of kids from London’s Croydon district, the two most important of whom are nice guy Enn (Alex Sharp), which is short for Henry, and rough, roguish Vic (AJ Lewis). Together with John (Eddie Lawrence), the tubby, horny sidekick who quickly fades from the story, they’re addicted to the new punk scene, and worm their way into a club where a raucous screamer called Slap (Martin Tomlinson) does his routine before a record exec brought to see him by his manager Boadicea (Nicole Kidman, barely recognizable in her wig and costume—lucky woman).

The gig goes bad as Slap is deliberately offensive to the exec, but there’s chance for some fun at the afterparty, so our intrepid trio go off in search of it. They wind up instead at a bash of sorts in a for-sale mansion taken over by an odd group dressed in brightly colored, skin-tight latex outfits who engage in bizarre synchronized dances and slink about suggestively. Eventually it becomes clear that they’re not just some crazy cult but a bunch of alien travelers who are going about the universe to investigate other species. The explanation that’s ultimately offered for their journey isn’t terribly coherent, but it has something to do with their decreasing birth rate and population—both of which might be related to their reputed consumption of their offspring.

That procedure is part of the rulebook that the aliens are compelled to follow unreservedly, something enforced by the travelers’ overseers—Stella (Ruth Wilson), who leads Vic upstairs for some intimate observation; Wain (Matt Lucas), a thoroughly unyielding sort; and a grey-haired androgynous matron called First (Edward Petherbridge). Enn, left downstairs to mingle, winds up alone with Zan (Elle Fanning), who fascinates him not just with her ethereal beauty but her Mr. Spock-like conversation.

While Vic is horrified by his experience with Stella and insists that they all escape, Enn and Zan have clicked, and her more lenient overseer Waldo (Tom Brooke) arranges for her to get a two day’s leave to go off with him, though he keeps track of her by taking over the bodies of others, like Enn’s likable mum (Joanna Scanlan) as conduits for his ministrations. Over the course of her earth vacation, Zan will experience the punk scene, even taking the stage in place of Slap, and she will return pregnant to her colony—a circumstance that proves a crisis for the overseers and leads to a debate over whether the rulebook should be changed. For some reason, it also initiates a confrontation between the aliens and the punks. A supposedly heartwarming coda, set fifteen years later, has Enn, now a successful Gaiman-like author (Sharp in very unconvincing makeup) learning the result of his relationship with Zan.

This précis, quite honestly, makes Mitchell’s “How to”—as opposed to Gaiman’s—sound far more intelligible than it actually is. In reality the movie is a muddle that doesn’t so much extend the original story in interesting ways as bastardize it by imposing the director’s all-too-obvious obsessions on it. In the process Mitchell doesn’t even bother to make his additions comprehensible; the movie just ambles along lackadaisically, randomly making things up as it goes along in a failed effort to appear vaguely thought-through.

Matters aren’t improved by the slapdash style—marked by garish costumes, flashy music, robotic movement and goofy dialogue—done up on what looks to have been a poverty-row budget. Mitchell apparently wants to make the movie look distinctively odd, but he doesn’t possess enough of a visual sense (or the necessary degree of directorial control) to pull it off; it winds up a mess. Nor has he the ability to draw much from his actors; Fanning is just blandly blank, and Sharp—whose Broadway performance in “The Curious Incident of the Dog in the Nighttime” earned accolades—offers little but enthusiastic, unvarying boyishness here. Scanlon offers a few moments of giddy fun, but no one else in the supporting cast makes much of a positive mark.

In retrospect, any attempt to adapt Gaiman’s story for the screen—except in the form of a half-hour “Twilight Zone” episode—was probably doomed by its reliance on mood over plot. Mitchell’s might aim to be another “Rocky Horror Picture Show,” but is more likely to wind up on Mystery Science Theatre.