At about 3.30pm this afternoon The Avalanches posted a mysterious photo on their Facebook page.

It showed a long black envelope with a gold butterfly on it – the motif for their latest album Wildflowers – and a post that said "#avalanchesgold," with a longitude and latitude of -37.800276,144.983665.

Broadsheet dispatched a reporter to the site immediately: Bad Frankie in Greeves Street, Fitzroy.

There were two envelopes, both with a handwritten letter in gold sharpie and two tickets inside for a concert: The Avalanches are playing a January 4 show at Melbourne Town Hall.

One envelope was under the bar, another tucked under a speaker.

One of the envelopes was picked up while Broadsheet was on the scene. The other one remains. So if you're in Fitzroy right now, move.