After being arrested and interrogated, Aaron Stampler (a stuttering altar boy accused of killing a priest) becomes Roy, his split personality. Roy is a confident, tough-talking sociopath who dishes up the truth about the sex-deviant priest who abused Aaron and others.
The twist:The twist comes after the case closes when Aaron/Roy reveals to his lawyer that there is no stutter, no split personality and there never really was an Aaron. He made him up to get away with murder!