Three people die suspiciously in a family's home and the couple who have an autistic four year old son who is bullied begin to suspect he's involved. In fact he isn't their son and through a mix-up is actually the son of a murderess. A special-ed teacher is hired by his parents to teach him to speak.
James Brolin is the detective who has the job of questioning the boy. At last the mix-up at birth is discovered. The boy's real mother is in prison.