It turns out that the kid was kidnapped by who we thought was his father. His real father died in a car crash. Kidnapper makes off with the kid, who has lived with him for the last 10 years. The kid believes the story told to him by his fake father that mom and sis died in a fire. When the show up he refuses to believe that they are his real realitives.
The kid gets charged with murder, goes on trial and is eventually found not guilty by reason of mental defect. Lots of ‘who is really responsible’ type of comments by everyone.