Reade was known for writing "novels with a cause." Here, as in several other of his novels, his cause is the deplorable condition of mental hospitals in the early to mid-nineteenth century. Until late in the century, many considered the mentally ill untreatable. Hospitals were more like prisons than places for treatment. Admission policies were also fairly lax. Reade records a common fear that healthy people would be incarcerated.

In Hard Cash, a father incarcerates his son in order to cover up a crime. The doctors who admit him have a kickback scheme worked out with the hospital--they get money for each patient admitted. Once in the hospital, the hero tries to prove his sanity but finds it impossible to battle against doctors who refuse to look past the diagnosis that caused his admission to his actual mental condition. He also must negotiate with the head of the hospital, a woman who is madly in love with him and refuses to allow him out of her sight.

He cannot prove his sanity and only escapes when there is a fire in the asylum. There is one "good" doctor in the story who refuses to bleed patients, deny them food, or admit the sane to mental hospitals. The other doctors think him a quack, but he saves several lives.