Return of the King

Ok I have an adventure idea that is based on the Crown of ancient glory (don't have the adventure, just thumbed through it). Anyhow here is the story.... 20 years ago the queen of the land was in labour and she delivered twin boys. The queen unfortunatly died during the ordeal. The king was grief stricken and made a hasty decision...the kingdom had just come through a civil war and the king was concerned that when he was to pass on the crown to the eldest twin the youngest twin might rise up and the country would be plunged into civil war again...to avoid this the king had the youngest son taken by a LG cleric to be raised by others. The cleric gave the task to one of his most trusted servants. The king did not want to know or want the cleric to know where the youngest twin was....Fast forward 20 years....the king was killed in a battle fighting an orc horde and his crown was lost. The oldest twin needed the crown to have the support of the nobles so he could become king. While he was out searching for it bandits attacked the prince and killed him. The king did have a daughter who could have ruled in her brother's place by she became mad a short time ago. The king's cousin is out looking for the crown as he has designs on the throne....enter the PCs the cleric who had the younger twin hid is still alive, he doesn't trust the king's cousin and belives that he is behind the dead of the prince and the madness of the princess. The players have to locate the younger twin and find the crown....

Here are some ideas that I may use...
#1...Everthing is as is no plot twists...the kings cousin is evil and behind the death of the prince and madness of the princess.

#2... the cleric wants to take the crown for himself and is behind the death of the prince and the madness of the princess. He is playing the players as saps. The kings cousin isn't necessarily good or evil.

#3...(the one that I'm leaning towards)..the princess is behind the death of her brother. she is faking her madness because she learned of her younger twin brother ( she can only rule if there is no male heir). so she is faking to draw out her brotherand have the players locate the crown. The kings cousin isn't necessarily good or evil.

#4... any suggestions that you have to make this plot better?

#3 - The Clerics have cast Heal on the Princess, for the express purpose of healing her insanity, but it doesn't seem to work... She is still in a state of "paranoid dementia", where she hoards scissors and small weapons, and believes others are "out to get her, too"!

At the appropriate time, after the Prince is found, she plans to use her "dementia" as her cover for murder, if caught. In the meantime, she is always armed.

#3 - The Clerics have cast Heal on the Princess, for the express purpose of healing her insanity, but it doesn't seem to work... She is still in a state of "paranoid dementia", where she hoards scissors and small weapons, and believes others are "out to get her, too"!

At the appropriate time, after the Prince is found, she plans to use her "dementia" as her cover for murder, if caught. In the meantime, she is always armed.

If the Princess is insane as per the spell, I'm not sure heal fixes that. It takes something more powerful.

Anywho, have you considered allowing the other twin to be one of the PCs? That might be an interesting twist.

I like the idea, and you could consider a touching moment where the twin comes to his senses, cures his sister, and sees her take her place on the throne.

Is this an identical twin, or a fraternal twin? If it's an identical twin, there's going to be problems with people recognizing him, and believing that he is the prince. If word spreads of this, the evil cousin could find out and send assassins out after him. A simple divination would reveal that "the queen had twins" to know he was legitimate.

If things are as they seem, you've got the beginnings of a sort of divine right world where the lawful heir to the kingdom will govern well and justly but a usurper wickedly and unjustly.

You might well expand upon this in other areas. The land itself might wither through droughts, heat waves, etc while the usurper sits upon the throne. Magic items might well remember who their owners were and behave as cursed items for any who attempt to use them without the right to do so. (Turin Turambar's relationship with his sword might be a useful example of this--when it finally spoke, it said that it would be happy to kill him in vengeance for the blood of his master Beleg and the village leader who Turin slew unjustly. Similarly, in the Lord of the Rings, Aragorn could use the palantiri with less risk than others since, as the heir of Isildur, they were his by right. IIRC, the gold of the Rhine maidens in the Ring of the Niebelung had a similar curse). That would sharply differentiate the setting from standard D&D fantasy and would give it a more Arthurian/Tolkeinesque/mythic feel.