SYDNEY, 1923: a suitcase washed up on a harbourside beach reveals its grisly contents - and from there, an extraordinary story unfolds.

True history that is both shocking and too real, this unforgettable tale moves at the pace of a great crime novel.

In the early hours of Saturday morning, 17 November 1923, a suitcase was found washed up on the shore of a small beach in the Sydney suburb of Mosman. What it contained - and why - would prove to be explosive.

The murdered baby in the suitcase was one of many dead infants who were turning up in the harbour, on trains and elsewhere. These innocent victims were a devastating symptom of the clash between public morality, private passion and unrelenting poverty in a fast-growing metropolis.

Police tracked down Sarah Boyd, the mother of the suitcase baby, and the complex story and subsequent murder trial of Sarah and her friend Jean Olliver became a media sensation. Sociologist Tanya Bretherton masterfully tells the engrossing and moving story of the crime that put Sarah and her baby at the centre of a social tragedy that still resonates through the decades.