Giuseppe (Pete Posthlethwaite), Gerry Conlon's (Daniel-Day Lewis's) father, dies in prison. After 15 years, activist and lawyer Gareth Peirce (Emma Thompson) discovers some compelling evidence that had been intentionally concealed from the public, so the system could justify its injustice against the entire family of Gerry; eventually, she gets to submit an appeal, and, in a very forceful audience, she makes Chief Inspector Dixon (Corin Redgrave), look inept, and struggles to have the entire family revindicated.
Sadly, no legal action is taken against any of the officers who were in charge of the original investigation. Nonetheless, Gerry and all the others are acquitted and released; however, by the end of the movie, there was no intention to clean Giuseppe Conlon's name of the incident, so Gerry expresses that he would go on in his fight to achieve that goal.
Thanks Dr Mat!