Underworld features intriguing mugshots of police suspects from 1920s Sydney, documenting the denizens of the criminal underworld, from stone-cold gangsters to wayward youths, and providing a remarkable rogues' gallery of thugs and thieves, prostitutes and pickpockets, white-collar opportunists and blue-collar gunmen.

The images are selected from a collection of more than 2500 glass-plate negatives, part of the New South Wales Police Forensic Photography Archive held at the Justice & Police Museum in Sydney.

Never intended for public consumption, they are unique among international criminal portraiture. Suspects smile, laugh, snarl, or sneer at the camera and each image is infused with the sitter's personality.

The accompanying essays ponder the remarkable aesthetic of the images and document the rapidly changing postwar world, exploring how new trends in crime played out on the streets of New York, Paris, and Sydney.

The stories of the suspects shine a light on the dark side of the Roaring Twenties in Sydney.