Not many R&B gigs are heralded by an emcee in shirt, tie and top hat purring the promise of "an interactive emotion picture" like a huckster at a fairground. Few begin with their leading lady and two dancers cowled in black like executioners while an overture plays out. But this is the live show of singer and would-be android saviour Janelle Monáe, who has come to shake up urban music. The normal rules of engagement don't apply.
As an urgent opener, "Dance or Die", sets her four-man band into funk motion, Monáe shrugs off the hooded cape to reveal a black-and-white get-up of jodhpurs, high-necked Victorian shirt topped off by a defiantly directional Afro quiff. There's a hint of Grace Jones here, minus all the flesh, a little bit of inscrutable Bond villain, some of Erykah Badu's imperious blankness. There have been many unconventional get-ups adopted by urban artists since Hype Williams put Missy Elliott in a billowing bin liner for her early single "The Rain (Supa Dupa Fly)", but few have been so fascinatingly chaste.
In the blink of an eye, the band launch into "Faster", the first of many breakneck pop songs that recall OutKast, Monáe's fellow Atlantan free-thinkers. Without pausing for breath, they segue into "Locked Inside", a soulful pop lament about the battle of the sexes that is pure Lauryn Hill. Monáe's quiff comes loose a few times, disrupting the impression of a laced-up asexual dominatrix with her funk on. But the 24-year-old recovers brilliantly, dancing harder, tucking her errant locks back into formation. There has been no time to applaud until now, and when the cheers come from the hot, squashed crowd, they are explosive.
It is a given that Monáe's next London stage will be bigger. This show sold out in a few hours, thanks to her justly burgeoning profile. In 2006, she was an unknown guest singer on a low-key OutKast album (Idlewild) with a creative coterie – The Wondaland Arts Society – that continues to function as a southern analogue to Lady Gaga's ideas factory, Haus of Gaga.
Monáe's 2007 EP, Metropolis Suite I (The Chase) was nominated for a Grammy, and since then she has signed to Sean "Diddy" Combs's label and become a Letterman-guesting, goalpost-shifting funk-hop force.
Just in time, you might argue. American R&B and hip-hop spent the late 90s and the early part of the new century being spectacularly inventive, with mould-breaking artists like Missy Elliott and OutKast reimagining the genre with elephant noises and eclectic steals. As the past decade petered out, though, the humour and audacity seemed to dry up, and R&B was back to its old tricks, sonically staid and disrobing as a matter of course.
Monáe is the antidote. Inspired by Fritz Lang's sci-fi landmark Metropolis, her works are, seemingly, concerned with a robot called Cindi Mayweather, whose loose brief is the salvation of oppressed androids. The concept fills three suites of songs, divided over Monáe's EP and her imminent debut album, The ArchAndroid (out next week). Clearly, though, Monáe isn't talking only about robots. Black-and-white footage of Muhammad Ali, James Brown and the civil rights struggle plays out behind the band.
But the travails of downtrodden replicants from the future are just one of many narratives running through Monáe's dizzying constellation of ideas and influences, which span Walt Disney, Ziggy Stardust and Prince. Her dancers reappear sporadically, wearing creepy, white, long-nosed masks filched from a Venetian carnival; Monáe has a pair of shades designed by Salvador Dalí if he'd heard Two-Tone. After a brief break, accompanied only by guitarist Kellindo Parker – wearing shades and a shaggy black wig – she sings a Charlie Chaplin song, "Smile", previously covered by Michael Jackson. Monáe spent some time in New York studing musical theatre in between her Kansas childhood and her Atlanta rebirth, and it shows.
Concepts can get in the way of fun, but there is little danger of that here. Monáe's band are combustible, exploding without warning into a single, "Cold War", with superbly drilled showmanship. Monáe excels at such high-speed funk chases; her other superb single, "Tightrope", examines the line between high art and pop with unflagging bounce. Bolted together mid-set, "Cold War" and "Tightrope" make the walls run with condensation. But you forget to feel the heat, because Monáe's robotic abandon is so enthralling.
