The wise wizard Emril is dying of old age and wants to pass on his legacy to his only heir, Alaric, who is held prisoner in a dungeon, in a castle on an island in the middle of Moira Lake. Your reward for rescuing the boy will be one tenth of the legacy.
Notes
Palmer P. Eldritch was the pseudonym of Richard Hewison, used because he also worked for Telecomsoft at the time.