Packed into that set of "Who's Gonna Save My Soul" demos and alternate takes is this unreleased Gnarls tune "Mystery Man." It's a b-side collage stitched of a couple sketches -- Cee-Lo soulfully straining to a fat keyboard-and-backbeat vamp, bookended by a pair of Danger Mouse control-room geek-out instrumentals -- so while it's not Gnarls in fully realized pop mode, we do wind up with an interesting listen at the the pair letting loose and finding ways to save even their rougher ideas from the cutting room floor.