The Eyes of the Dragon was originally published in 1987. From StephenKing.com:
Once upon a time, in the Kingdom of Delain, King Roland is murdered and his son and heir, Peter, is framed for the crime. Peter and his loyal friends must battle an evil wizard and Peter's usurper brother, Thomas, for the throne. Imprisoned in a tower, Peter conceives an escape plan that will take him years to execute before taking on Flagg, the powerful sorcerer who has masterminded this coup.