Karl (Billy Bob Thornton)’s Timeline and Summary

After being interviewed by a student journalist, Karl is let out of the mental institution he has lived in for almost his entire life.
Time to party.
Karl wolfs down a pile of French-fried potaters, then tries to return to the institution.
The law doesn't allow Karl to return, so the hospital administrator finds Karl a job and a room in town.
Karl works repairing lawnmowers and befriends Frank, a young boy in town.
Soon, Frank's mom, Linda, invites Karl to stay with them.
Both Frank and Vaughan, Linda's friend, tell Karl that Linda's boyfriend, Doyle, is dangerous.
Doyle is loud, angry, and mean. He breaks windows, pushes Linda, and verbally abuses Frank.
Seeing enough of this, Karl sharpens a blade and kills Doyle, thinking it's the right thing to do.
Karl gets put back in the mental institution, where he appears to live happily ever after, like a Disney princess. Princess Karl.