Bull joins the district attorney in a case against Kara Clayton, who claims she killed her billionaire husband in self-defense, tensions run high when he learns that his on-again, off-again romantic interest, Diana Lindsay, is defending the widow.Bull joins the district attorney in a case against Kara Clayton, who claims she killed her billionaire husband in self-defense, tensions run high when he learns that his on-again, off-again romantic interest, Diana Lindsay, is defending the widow.