Ronnie Winslow, a 14-year-old cadet at the Royal Naval College, faces an unjust accusation of stealing a five-shilling postal order. An internal investigation, carried out without notifying his family and devoid of any representation, concludes with a guilty verdict. As a result, his father, Arthur Winslow, is compelled to withdraw Ronnie from the college—a euphemism for expulsion. Deeply convinced of his son's innocence, Arthur joins forces with his daughter, Catherine, a strong-willed suffragette, and their trusted family solicitor, Desmond Curry, to fight for Ronnie's name.
The stakes are high; under English law, Admiralty decisions cannot be challenged without government consent. Traditional wisdom dictates that any effort to question these acts must go through a lengthy process involving the attorney general. However, the Winslow family is unwavering in their determination.
In a significant turn, they engage Sir Robert Morton, the foremost barrister in England at that time. Known for his keen political acumen and as a formidable opposition MP, Sir Robert initially seems a reluctant participant. Yet, to Catherine's surprise, he quickly becomes convinced of Ronnie's innocence after conducting an impromptu interrogation that resembles cross-examination. With his characteristic composure, he advocates for the Winslows in the House of Commons, gradually mustering the political influence needed to challenge the case.
Despite government resistance, which sees the case as a nuisance, the changing tide of public opinion, fueled by the Winslows' efforts, forces the authorities to relent. As the trial unfolds, Sir Robert, alongside Desmond Curry, effectively dismantles the prosecution's arguments, leading the Admiralty to retract all charges and declare Ronnie innocent.
While the legal victory restores Ronnie's reputation, it takes a significant toll on the Winslow family. The emotional strain has severely impacted Arthur's health and family happiness. Financial burdens also emerge as the costly suit consumes funds allocated for Ronnie's brother, Dickie's, education at Oxford, jeopardizing his career ambitions. Furthermore, Catherine’s marital prospects dissolve as her fiancé, John Watherstone, breaks off their engagement due to pressures from his military-minded father. A sincere yet unreciprocated proposal from Desmond emerges as an uncomfortable option for Catherine.
Notably, Sir Robert chooses to forgo an appointment as Lord Chief Justice to prioritize the case, a decision that signifies his commitment. The play concludes with an intriguing potential for romance between Catherine and Sir Robert, both of whom acknowledge their misjudgments regarding each other. The final lines encapsulate this evolving relationship:
> "How little you know women, Sir Robert."
> "How little you know men, Miss Winslow."
