It's 1843 and England is in turmoil. The country is rocked by strikes, demonstrations, and calls for armed rebellion against the Crown's repressive policies. Daniel M'Naghten is a Scottish workingman and outspoken critic of the Tory government. He suspects that their agents are spying on him and plan to kill him. He flees to France, but they follow him. He escapes to London and formulates an audacious plan; he will assassinate the man responsible for his troubles, Sir Robert Peel, the Prime Minister of England. His plan works almost perfectly, except he shoots the wrong man and kills Edmund Drummond, Peel's secretary. M'Naghten is arrested, charged with murder, and awaits trial in Newgate Prison. Alex Cockburn is a barrister who, despite his family's wealth and title, represents unpopular causes. Representatives of the Crown ask him to defend M'Nagthen and Alex, encouraged by his friend and confidante, Charles Dickens, takes the case. His investigation uncovers evidence of a secret government conspiracy and raises serious doubts about his client's state of mind. The trial of Daniel M'Naghten is an overnight sensation and captures the attention of the public, the press, and the Crown. The Queen demands that M'Nagthen must hang for his crime and Alex finds he is faced with a terrible choice, serving the Crown or saving his client. M'NAGTHEN'S RULES is inspired by a true story.