Ronnie Winslow (Neil North), a cadet at the Royal Naval College, Osborne#Naval College, is accused of the theft of a postal order. An internal enquiry which grants him no chance of defence, finds him guilty and his father, Arthur Winslow (Cedric Hardwicke), is requested to remove his son from the college. Unwilling to accept the verdict, Winslow and his daughter Catherine institute their own enquiries and engage a friend and family solicitor, Desmond Curry (Basil Radford) to assist them, including the briefing of the best barrister in England at the time, Sir Robert Morton (Robert Donat), should the case come to court.