On Thursday 1 July, 1999, Dr Nina Simone gave a rare performance as part of Nick Cave’s Meltdown Festival. After the show, in a state of awe, Warren Ellis crept onto the stage, took Dr Simone’s piece of chewed gum from the piano, wrapped it in her stage towel and put it in a Tower Records bag. The gum remained with him for twenty years; a sacred totem, his creative muse, growing in significance with every passing year.