A long time ago in a faraway land, there lived a lovely young princess named Margarita. Her beauty and grace were known throughout the land - especially to to Mad Mizer, the Dark Lord of the grim Groken Castle high in the Forbidden Mountains. He had vowed to make the Princess his queen; and
so, one terrible day he sent his ghoulish helpers to capture her, and she was carried off and imprisoned in one of the hundred miserable rooms of Groken Castle.
News of the kidnapping spread throughout the kingdom, and many courageous young men braved the perils of Groken Castle in an attempt to rescue the Princess, only to become hopelessly lost in the complicated maze of rooms, ensnared in one of the many treacherous traps, or foiled by Mad Mizer's deadly servants.
Finally the news reached the worthy Prince Rafael, who had long loved the Princess from afar. Raising his sword to the heavens, Prince Rafael swore that nothing would keep him from her side, and set out on his Castlequest. The odds against him seemed hopeless... But legend has it that two magical Fairies have been held captive in the Castle for centuries. If the Prince can find and release them to gain their help, he may yet succeed in his quest. And to rescue his fair Princess, he is prepared to face the deadly wrath of the Dark Lord himself!
--From the NES Castle Quest instruction manual.