Recently arrived from Port Macquarie, ticket-of-leave gentleman convict Hugh Llewelyn Monsarrat now lives in a small but comfortable house in Parramatta with his loyal housekeeper, Mrs. Mulrooney.
Monsarrat is now working for the Attorney General's office, officially as a clerk, but also as an unofficial advisor on criminal and legal matters. One day, he is informed that the superintendent of the female prison, Robert Church, has been murdered.
Apparently, a female convict named Grace O'Leary held a particular grudge against him and is being detained for questioning. Monsarrat's task is to take a statement from her. Grace doesn't strike Monsarrat as a murderer and she insists she's innocent. Monsarrat and Mrs. Mulrooney both believe her, but are at a loss as to how to help her. A number of people held grudges against Church and many are relieved by his death, but who would go so far as to murder him?