One morning in September 1852, a handsome couple stepped onto a hired boat bound for Ireland's Eye, an uninhabited island and popular tourist spot off Howth Harbour. William was an artist of considerable means and his wife, Maria, a keen swimmer. After sunset, when the boatmen returned to collect their customers, Maria was missing.

A search was mounted, and she was found dead in a lonely, rocky inlet. The inquest ruled the death a drowning, and Maria Kirwan was laid to rest. Soon after, a startling secret sparked an investigation, Maria's exhumation and William's arrest for her murder.

The story caused a sensation: a secret life and a sharply divisive trial that aroused the full force of Victorian moral outrage. A veil of mystery has hung over Maria's death for almost 170 years. Now, this modern analysis casts more doubt over the Crown's version of events than ever before.