This film was loosely based on the famous Massey divorce proceedings. At the beginning of the movie, Doris Attinger (Judy Holliday) shoots and wounds her husband Warren (Tom Ewell) when she catches him in the arms of his mistress. Assistant DA Adam Bonner (Spencer Tracy), a hard-nosed, law-respecting, somewhat conservative man is assigned as the prosecutor to put Doris away. Hoping to take a public stand for women's rights and a private stand against her husband's somewhat antiquated beliefs, his wife Amanda Bonner (Katharine Hepburn) decides to represent Doris at trial against her husband.
The trial is highly public and causes much strain on Adam and Amanda's relationship to the point where Adam moves out. After Amanda turns the trial into a media circus, Doris is found not-guilty. Adam and Amanda watch as Doris, Warren, and the mistress preen together before photographers and revel in their newfound fame. The fighting between Adam and Amanda escalates when Adam bursts into their neighbor's apartment where Amanda was celebrating her victory, aims a gun (later discovered to be made of licorice) at Amanda and her neighbor, accuses them of having an affair, and tricking Amanda into admitting her defense of Doris was wrong.
At the end of the movie, the two reconcile while doing their taxes and remembering all the good times they shared. Adam and Amanda also gain a new respect for each other and their respective legal abilities and philosophies.