This takes place during medieval times but has a fairytale twist to it where there are four kingdoms that rule about the land;
Kingdom of Miriena,
Kingdom of Ribaen,
Kingdom of Coranne,
and Kingdom of Tiath.

Each Kingdom at this point and time have one ruler, their significant others already passed away.

The impulsive King Frederick ruled Miriena.
The sympathetic Queen Alexandra ruled Ribaen.
The belligerent Queen Eleanor ruled Coranne.
The humble King Jeffrey ruled Tiath.

One day, all four rulers were poisoned but an unknown source, and all passed away by the end of the day, leaving their heirs to unexpectedly take over for the Kingdoms.

Whoever poisoned the rulers has not been found yet, but they know it must be a minimum of four people working together as it would be impossible to travel to all four Kingdoms in a days time.