So I have this idea of a murder mystery set in a fantasy setting.

The crime scene would be a massive festive gathering among the Noble elite in conjunction with a solar eclipse. The King has been absent for some time due to fighting in a war, but has returned to fulfill his Kingly duties on this sacred day. During the night celebrations filled with dancing and booze tragedy strikes when not the King dies, but his youngest son! How? Poison! How? A goblet of beer meant for the King but snuck to his son in an innocent bonding gesture.

In terms of the killer I have the idea of them being known as the “Gold Mask” in reference to gold masks worn by servants during the ceremony, the belief being that the killer must’ve been dressed as a servant to slip in the poison.

Motives I’ve come up with are kinda basic imo: a secret murder ring that doesn’t support the King’s rule & wants to change gov’t structure; the Gold Mask being a foreign assassin-for-hire; the killings being copycats of past mysterious unsolved murders; and the killings being linked to the past unsolved murder of the King’s late twin brother.

I don’t hate these motives but I’m just struggling to brainstorm something that really makes me go “ooh! yessss” if you catch watch I mean.

For context: the world is set on disparate islands that have settled into major cities that occasionally go under Domes to handle dangerous storms. The War the King has been fighting in has been against a newly discovered island’s inhabitants that seem to harbor long lost dark abilities.

If anyone has any random motive ideas they have and would like to share to maybe help me brainstorm that would be great! Or if you came up with one based on this that’s great too! :)