Broken Bells, Royal Festival Hall, London

Greeted with an awed silence from the packed Royal Festival Hall, James Mercer (singer-songwriter and brains behind jingle-jangle indie outfit The Shins) asks an impromptu question that catches his enraptured audience off-guard. "Anybody here skateboard?" he enquires optimistically. "I used to skate at Southbank before it was a skate park. This is my homecoming," he explains, with that tone of wistful poignancy that characterises his work to date and manifests itself in the lovelorn lyrics of the track that follows, "Trap Doors".

Handpicked to play the Meltdown Festival by this year's curator, Richard Thompson, it is easy to see why the experimental brand of psychedelic indie made by Mercer and his partner in Broken Bells, Brian Burton (aka Danger Mouse, one half of Gnarls Barkley), has gained such strong support already.

Commencing with Burton on keys for the haunting "October", the duo and their five auxiliary band members are lit by trippy visions of galaxies and geometrics as their sound builds to a melodic clamour.

New single "The Ghost Inside" finds Burton on the drums. His subtle beats perfectly compliment Mercer's falsetto, offering the song a more complex result than the polish of the record allows.

"Sailing to Nowhere" provides strings and keyboards that resonate with the lilt of an old-fashioned fairground, while a cover of Tommy James and the Shondells' 1969 hit "Crimson and Clover" introduces a rockier folk tangent to the mix. Though, perhaps undeservedly with such a diverse showcase, it is still the single "The High Road" that earns the biggest cheer.

The duo save the best til last, with Mercer going acoustic for "Insane Lullaby" from Burton's forthcoming album, Dark Night of the Soul, before the encore of "Hold on Me" and the thrilling "Mongrel Heart". Despite the hall's acoustics creating a recurrent distorted resonance, Broken Bells are extraordinary.